Paradigm:
I think we mix up the discussion here (probably my fault). It's not only the Mana Drains that helps the control-first-combo-later gameplan but also the additional togs and maindeck berserk. And keeping UU open was not much of a difficulty because as i said earlier, you didn't really try to force the deck to be as fast as possible. Sometimes you held on to your gush so you could use it as Wasteland protection or if you already made your land drop for the turn. But maybe this just is a matter of playing style, i haven't played that much against the new metagame of flash and ichorid, so its hard to tell.
To answer your questions.
1) I'm not sure that 4 mana drain is the way to go, maybe 3 och even 2 might be the right number. If i would cut something from the list presented earlier in this thread i would probably cut regrowth, merchant scroll 3 and 4. Maybe the forth duress. Lotus Petal and Strip Mine, the street wraiths (but well, then i would include sleight of hand instead). Those are the cuttable cards in my opinion.
2) Hard to tell, there are significant differences for sure. Back then you faced a lot of blue based control decks and workshop aggro. None of which are any part of todays metagame (after gifts restriction, even though my limited playtesting with a mind twist control deck showed some promise

). Ichorid is a completely new kind of deck and combo is faster and more played. So, i really don't know

. But i think it is safe to say that the 2007 metagame is much faster than the 2003 metagame. So maybe thats why mana drain doesn't fit. But still, wouldn't more togs and maindeck berserk suit a faster metagame?
I'm not saying that "this is the way it should be built!!", because i have no idea, i just wanted to ask the questions that came to my mind.