I just want to throw one thing out there. I don't buy this suggestion that D'Antoni's system "falls apart in the playoffs". I think its the other way around. It lifts teams in the regular season.
Basically, D'Antoni's system (along with Nash to run it) was effective in making pretty mediocre teams, REALLY good, especially in the regular season.
Look at their 2006-07 team, which won 61 games (a high for D'Antoni). They were built around Nash, Amare, and Marion. Good, but not great players. Then they had Barbosa, Bell, and Diaw. That's not spectacular talent. Honestly, they may have even been overachieving to make it to the second round in the West that year (Beating the Lakers, and then taking the eventual champion Spurs to 6).
I think D'Antoni's system is no different than Sloan's, or Jim O'Brien's, or any other coach that thrives at getting teams to play above their head. And for all of these guys, the question is, is the system holding them back from winning championships, or is their lack of talent holding them back from winning championships, and their systems are just putting teams in contention that really have no business being there?