You've left out the big one for many people: fully-independent FSB adjustment with no impact on the PCI bus speed. No fussing with dividers and ratios to overclock without destroying one's hard drive.
Then there's DDR400 support. KT400? One DIMM, officially speaking. nForce2? Three DIMMs, both officially and in practice.
Then there's 400MHz FSB support. KT400? Haha, did you think the "400" meant... oh, you did? Good one, huh?

nForce2? Sure, with a BIOS update when the time came.
Then there's PCI performance. I had a KT333 board and no way could I get more than 72Mb/sec throughput on the PCI bus. With nForce and nForce2, I can hit over 120Mb/sec from my SCSI card to the PCI bus, which is about the practical limit for PCI when you factor in overhead. Did KT400 fix that? I don't know, but somehow I doubt it.

I did give both Asus and VIA detailed bug reports, but never got an acknowlegement.
Dual-channel memory got people up in arms since they were initially expecting huge performance boosts, forgetting that even in single-channel mode, nForce2 was already cleaning KT400's clock. Oh wait, you were one of them :Q no offense meant! (pulls foot out of mouth

) Soon we will have some single-channel nForce2 boards to look at.