Hmm. I'd have Hadlee over Steyn anyway. I
also think Miller over Procter (slot Miller in at 5 and slide Sobers and Gilchrist back to their real positions).
I daresay that the second side you've picked would probably lose more often on juicy decks and win/ draw more often on roads.
All rounders and tail end batsmen tend to perform far better in easier circumstances while genuine batsmen tend to adapt better to difficult circumstances, particularly the top class batsmen.
Hadlee and Steyn are a bit of a toss up for third best quick ever in my mind. Hadlee would be my second pick after Marshall if I was trying to construct the strongest team, but McGrath and Hadlee are too similar in bowling styles, so Steyn gets the nod. If you aren't a big Steyn fan, he can be subbed out for just about any ATG bowler, I just wouldn't want it to be Hadlee if trying to pick the strongest bowling lineup.
Leaving Miller out is a knock-on effect from Imran. I think teams should be picked on their average career, not at the best. Imran is an atg fast bowler, but due to his changing career roles, you can't really consider average career for him. In an ATG side, I'd consider it fair to say if picking Imran the side should be picked to play 88 matches, and Imran plays a proportion representing his various stages of career quality.
I consider Miller very balanced, but if anything to be, a batting allrounder who overachieved with the ball and under achieved with the bat. And he only picked up around 3 wickets a game. He would bring perfect balance to the side with an average career Imran, but with a representative career Imran, the first side is going to be clearly ahead in the bowling department in too high a proportion of matches, which makes the exercise less interesting. It also makes the second side a definitely stonger batting unit in my mind, which is again less interesting.
On the tail overperforming in tricky circumstances (pitch conditions or quality of bowlers) and underperforming in tricky ones, I tend to agree, and think this team should mostly be picked with tricky ones in mind. However, the second tail is so much stronger that I consider the batting stengths of the teams very comparable anyway.