I have a lot of experience playing suicide black in powered enviornments. During the height of fish, it even won several 15-20 people tournaments at neutral grounds having a favorable matchup against both Fish (u/r) and GAT and ok matchups against 4cc and Tog. However with workshop decks becoming more and more popular and with Oath being an unwinnable matchup, i decided that the deck needs a major revamp.
For refrence here is the original decklist of my sui and my starting point.
// Mana
15 Swamp
1 Black Lotus /Swamp in the budget version
1 Mox Jet /Swamp in the budget version
1 Strip Mine
4 Wasteland
// Creatures
3 Nantuko Shade
4 Phyrexian Negator
4 Withered Wretch
3 Hypnotic Specter
// Spells
1 Necropotence
1 Diabolic Edict / Nice tutor target
4 Dark Ritual
1 Demonic Tutor
4 Duress
4 Hymn to Tourach
4 Sinkhole
1 Yawgmoth's Will
3 Null Rod
1 Vampiric Tutor
// Sideboard
SB: 1 Null Rod
SB: 2 Chains of Mephistopheles
SB: 4 Contagion
SB: 4 Planar Void
SB: 4 Smother/Powder Keg
Unlike most other aggro decks that rely solely on speed, sui works by attacking the opponent's hand and mana sources, restricting access to solutions, while the fast creatures demand they come up with those solutions or lose.
The problems arise when the opponent does come up with a solution. Suicide has no way to deal with troublesome permanents. Yes it kills small creatures post-sideboard quite efficiently (which is perhaps why i almost never lost to fish), however any enchantment or artifact threats can be deadly.
Since black simply does not have the utility to address the threats that hit play, the natural solution is to splash another color while maintaining the overall speed and threat frequency. This of course has the drawback of destabilizing the mana base a bit, however I believe that the benefits gained outweigh the drawbacks.
The question is what color is best to splash.
Looking at our options:
Green: This adds Pernicious Deed, Naturalize, Oxidize, and perhaps a few efficient creatures. Out of these, Deed is the card that really shines. However Deed is a slow control card and while adding a solution to low costing permanents, it goes against the spirit of this deck. I have played around deed before without much difficulty.
Blue: This adds a draw engine and counters. However at that point, sui becomes tog.
Red: This adds Blood Moon, Random Burn, Rack and Ruin/Shattering Pulse. While Welders really dont like the addition of burn, the deck still has no answer to enchantments.
White: The splash I decided is worth the most consideration. The card Vindicate, while being expencive mana-wise, fits right into this deck. White also offerst Swords to Plowshares to take care of almost anything an opponent Oaths or Tinkers out and Seal of Cleansing offers both enchantment and artifact destruction.
Here is the suicide list with the White splash.
// Mana
1 Plains
6 Swamp
2 Flooded Strand
4 Polluted Delta
4 Scrubland
1 Strip Mine
4 Wasteland
// Creatures
3 Exalted Angel
3 Phyrexian Negator
3 Withered Wretch
// Spells
1 Necropotence
4 Dark Ritual
1 Swords to Plowshares
1 Vampiric Tutor
1 Demonic Tutor
4 Duress
4 Hymn to Tourach
4 Sinkhole
4 Vindicate
1 Yawgmoth's Will
2 Crucible of Worlds
3 Null Rod
// Sideboard
SB: 3 Swords to Plowshares
SB: 1 Null Rod
SB: 4 Contagion
SB: 2 Engineered Plague
SB: 1 Humble
SB: 4 Seal of Cleansing
Note: power not added due to null rods and this being a budget deck, however I'm sure that substituting a lotus for one of the swamps would work.

Card Choices:
Vindicate: With 5 stips and 4 Sinkholes already in the deck, this card most frequently acts as a land destruction spell, resulting in a total of 13 ways to kill a land. However if your mana denial routine doesn't work and they do get out a threat that must be delt with, Vindicate deals with it. What i love about this card is that it's almost never dead. Just like every other card in the original sui, it's a threat that can be cast immediatly upon drawing it.
Swords to Plowshares: This card is self expanatory; however unlike Vindicate, StP can be a dead card against certain decks. My only concern is that in my current build i can only fit one in.
Exalted Angel: Yes it's double white, yes it has echo, yet it very frequently ends the game. 4cc has already proven that an 8 point life swing is nothing to scoff at, and with my deck being full of disruption spells, my opponent is frequently unprepared to deal with it when it flips. It also has nice synnergy with Necropotence.
Phyrexian Negator: 4 turn clock for 3 mana.
Withered Wretch: Deals with dragon, welder, and helps against tog. Great tech against a great number of decks.
Crucible of Worlds: If I ever run out of ways to destroy the opponent's mana sources, Crucible is here to help me reuse that wasteland. In a deck that runs ritual, a complete stip lock turn 2 is very possible. Can also help me get that last white mana source to morph up angel.
Vampiric Tutor: while being card disadvantage, it is an instant and only costs 1 mana. Also, unlike demonic consulatation, it doesn't kill you.
Sideboard Choices
Seal of Cleansing: Better than disenchant in that i can cast it on a turn when i have nothing else to do and then continue with my disruption routine.
Contagion: Has a tendancy to kill fish dead. In fact, almost every aggro deck groans when i kill two of their creatures for 0 mana.
Engineered Plague: Anti-Goblins tech.
Humble: Swords #5. Also stops most leaves-play abilities. Is probably a sub-optimal card.
Cards I'm considering
Balance: This has the potential to be a game breaking card, however much of the time it is more likely to be a dead card. I am constantly destroying my opponent's land and hand and i'm usually the one with more creatures in play. Still, i am tempted...
Serenity: ok it destroys my crucible and possibly a null rod, but at the same time it can destroy a lot of their permanents. Still slower than seal.
Sacred Ground: Makes sure my mana base is indestructable and ignores Sundering Titan, Smokestack and Wastes.
Matchups:
Oath: I may lose game 1 if they get a fast hand with both combo pieces game 2 however i bring in both seals and 4 swords giving me effectively 8 disenchants and 4 ways to deal the Colossus/Akroma/Spirit of the Night. Irridescent i can race with my own angel and pristine will be hard-pressed to stay untapped ALL the time.
Workshop and variants: My chances have improved. Even though opponent going first turn trinisphere when i start without a wasteland in hand STILL tends to spell quick death for me even with this build. Game 2, having 8 artifact destruction and 4 swords for welders makes it a bit easier.
4cc: Not only is cutting it out of several colors even easier than it was before, now i can even deal with a random angel with a Vindicate. My matchup has improved from ok to favorable.
Fish/Gat/Tog: Insufficient testing. Did win one match against GAT though.
In conclusion, i think splashing white may help revive the dying (dead?) suicide black decks and I eagerly await any input/suggestions any of you may have.