It think his point was that since all of your non-basics become mountains, you can still utilize them

Sure your Workshops don't produce as much, but non of your lands are locked out of effective use either.

Personally I have always liked the 5C variant, and for that variant, this is what I would consider a good starting point deck wise
4 Mishra's Workshop
4 City of Brass
3 Gemstone Mine
4 Wasteland
1 Strip Mine
1 Tolrain Academy
1 Mox Emerald
1 Mox Jet
1 Mox Pearl
1 Mox Sapphire
1 Mox Ruby
1 Black Lotus
1 Mana Vault (Sometimes removed because it can be a pain to untap, but this can be really useful getting stuff out turn 1)
1 Mana Crypt
1 Sol Ring
3 Crucible of Worlds (Insane with Wasteland or Strip Mine, and nice with Gemstone Mine if the game lasts too long, also helps recover from Smokestack)
4 Smokestack
4 Tangle Wire
3 Chalice of the Void (4th is nice but not necessary, as often the second Chalice hurts you just as much as them)
4 Sphere of Resistance
1 Trinisphere
1 Karn, Silver Golem
Other Kill Cards (Usually 2-3 other kills are included)
1 Tinker (Staxs "Oops I win if you don't counter" card)
1 Vampiric Tutor
1 Demonic Tutor
1 Imperial Seal
1 Ancestral Recall (3 cards is always nice)
4 Goblin Welder (Some don't run 4, or any at all, but I think this guy is too broken for less than a playset)

There are a large number of changes you can do from there, here are some that I have noticed
Crop Rotation (Turns a mutlicolored land into a Mishra's Workshop, Tolrain Academy, or Bizaar of Baghdad if you are running it)
Bizaar of Baghdad (Good with Welder and Rotation, be very careful, if you don't have any hand or cards in play it is really hard to win )
Balance (Droping a pearl and another mox or a 5C land and any artifact man makes your opponent discard at least 3, and all you lose is a land first turn, with the right hand it is even better, but on the draw or against certain decks it is sub optimal at times)
Darksteel Colossus (11/11 Indestructible Trampler is hard to deal with, but alot of decks run bounce now, so he has lost some of his flair, I love him tho )
Sundering Titan (Rapes mana bases, missing every land in the deck, and beats for 7 to boot)
More Karns (This guy sometimes just wins, but he is also legendary, and fetchable, so up to you really)
Barbarian Ring (Nearly uncounterable beating to the face that is reusable via Crucible is nice)
Platnium Angel (I can't lose, you can't win is awesome, but fails in even more ways then Darksteel when getting targeted)
Null Rod (Missing everything but your acceleration, since your locks are either game changing or triggered)
Leyline of the Void (Ichorid bypasses alot of this decks control methods, personally I don't think this is worth a MD spot, but debatable definatly for a SB spot)
Thirst for Knowledge (Draw 3 and give yourself Welder fodder is nice)

And finally, here is what I currently run, note that it needs to be refined a bit more still, and I need to make room for Imperial Seal still

//Land
4 Mishra's Workshop
4 City of Brass
3 Gemstone Mine
1 Tolrain Academy
1 Bazaar of Baghdad
4 Wasteland
1 Stripmine

//Artifact Mana
1 Black Lotus
1 Mox Pearl
1 Mox Emerald
1 Mox Sapphire
1 Mox Jet
1 Mox Ruby
1 Mana Vault
1 Mana Crypt
1 Sol Ring

//Kill Conditions
1 Karn, Silver Golem
1 Darksteel Colossus
1 Sundering Titan

//Tutors
1 Tinker
1 Crop Rotation
1 Vampiric Tutor
1 Demonic Tutor

//Lock Components
4 Tangle Wire
4 Smokestack
3 Chalice of the Void
4 Sphere of Resistance
1 Trinisphere

//General Utility
3 Crucible of Worlds
4 Goblin Welder
1 Balance
3 Thirst for Knowledge

I for one totally and completly agree with the way they changed Oboro Envoy

Much like how the original printing of Grip of Chaos was much unlike what the average player would think the ability would do, most players do not even notice the lack of "until end of turn" on Oboro Envoy, I know I for one didn't.

Most people have been ingrained with -X/0 to target creature means "until end of turn" intrisinctly.

Therefore I would think of the change to not be a power level errata, but a clarification to make the card functioning as the player thinks the card should function as printed not as the card functions as printed.

In fact this is probably where the problems with Phyrexian Dreadnought come into play, since the original card could not be stifled or anything along those lines, since the rules were much different then, no such thing as a stack etc. But looking at the card today, your average player says "Oh, its a triggered ability", so because of this, they decided to make it into a triggered ability again, even though the card now functions differently then it did when originally printed.


At the end of the day, errata is all about the preceptions about the cards, so there will never be a final, always correct answer. *shrug*