Amare actually has great vision when he chooses to use it, and one thing that's always impressed me for a guy who is a career 1apg type player, he almost always makes the right pass out of double teams. The way he has been used over the last few years in our offense is very atypical of the way many other top tier power forwards are used. Every time he gets the ball it was either to a) iso and go 1 on 1 facing up, either coming off a screen and getting the ball at the 17 foot marker in front of the basket, or from mid range on the wings, b) in a pick and roll with Nash, or c) that set play we always, always ran at the beginning of games for him to hand it off to Raja coming off a screen for a jumper at the top of the key. Those were the only three ways he was ever touching the ball. Don't sleep on his vision though, he might not have a lot of assists but many of them (especially when we still had Shawn) were in the spectacular fashion. He just needs to look at the basket a bit less.
I also don't think the Tyson Chandler thing is a legitimate excuse for West not being a good rebounder. Chandler averaged 11.7 boards in a little over 35 minutes per game, and Shaq averaged 10.6 in only 28.7 minutes per game which is a much higher rate. That's not an excuse for either guy in my opinion, they're both just sub-par rebounders.
And I agree with you about Duncan 100%, he is a true center in most aspects of the word. But he's played like, literally every single game of his career at power forward, so that's what he gets called. He made the All-NBA team is a forward when Amare made it as a center, even THIS year. It's just a weird situation I guess. I still don't think West is better than KG, Dirk or Amare though.
Edit: And as far as Duncan not being able to guard power forwards, I'm really not so sure about that. I thought Duncan did a very good job on Amare in our series, and he's not necessarily doing a bad job on West. He's not lightning quick but he almost never fouls, and even if he gets beat his arms are so long that he recovers to block a lot of shots. I think power forwards eating the Spurs up has much more to do with their defensive game plan (don't let a good 3 point shooting team beat you from the 3 point line) against teams like the Suns and Hornets than it does with Duncan not being an adequate defender.