Clown of Tresserhorn: As you say yourself your experience is with Spoils Mask and not Vengeur Masque. I completely agree with your critizism concerning Spoils Mask (I was so disappointed by that deck). However, Vengeur Masque is a different story and is by far the best deck of the two IMO.
To support this statetement I will focus on the points you raised about Spoils Mask's incapacity to compete and show that Vengeur Masque does not share these:
The deck relies on a "combo" that doesn't win the turn it's cast
It's based around a creature. An artifact creature. Soooooo many decks can deal with it. From Swords to R&R, decks now have a wide array of weapons to deal with dreadnoughts. Not to mention, it takes 2 attacks to finish an opponent. Decks like FCG and Tog get away with "comboing out" with creatures simply because they win if they get a chance to attack
Volrath's Shapeshifter (+ Phage) will win you the game right there and it is not an artifact. It can even win on the turn cast if you are using Lightning Greaves or Anger (in UGr Masque).
V. Masque has about the weakest manabase I have every seen. I played a few matches against it, and it was terrible (although I was playing landstill, a probably favorable matchup).
I don't know why you would say this. It hs BoPs and 2-3 Forest to protect it against Blood Moon and further it has 2-3 Quirion Ranger to protect it from Wasteland. I think your experience is biased by the Landstill matchup because I have never had any serious problems with the mana base of this deck.
I really don't see how V. Masque is much better than, say, TnT. You do get some counters, but with TnT, you get threats along with better, proactive disruption. I would GLADLY take bloodmoons, wastelands, and pillars over a set of forces.
Well, in addition to having FoWs it is better in quite a few ways - to list the ones I can think of now:
1) Ability to win in one turn by shapeshifter + phage.
2) More resilient to artifact hate.
3) Favorable matchup against TnT.
4) Better against Dragon (Due to FoW and a faster kill). Not a good matchup though.
Also, I play 3 Blood Moon in the SB of my current UGr list, so that card is not a reason to choose TnT.
Has anyoner considered FeverMask? I know it sucked in the past with Ankh sligh running rampant (It ran like 7 fetch lands), but ankh sligh is all but dead. It seems like it may work pretty well as it has a plethora of cantrips and cheap counters, as well as GREAT tutors in the form of lim-dul's vault.
I have, since I really liked the list back then. Sadly, I think Finkels are a tad bit slow these days, so I never got around to really test it. It would be great if you would take on the task, though
To sum up I definetly think Mask decks in the form of Vengeur Masque is a contender today. While it isn't the "best deck" it can take on pretty much everything and still has the advantage of being "undertested" by many players due to its relatively rare showings.
As regards to splashing in Vengeur Masque, I think it is hard to pick a best color. White gives you an edge against aggro (StP) plus Meddling Mage, black offers good weapons against control (Chains, Duress) as well as graveyard hate (Whittering Wretch) and red gives you Land hate in Blood Moon, artifact hate in Gorilla Shaman and Goblin Welder while also allowing you to play Anger.