Im in the market for a good stage piano/controller. I've heard the arguments, and if price was not an issue, which would you buy? I have other keyboards, so tons of sound aren't that important to me. I want durability and great action, with the most future potential (i.e. expansion.) If you have played both, I'd love to hear your opinions.

I haven't tried the A90ex, but I tried a QS7 - with the same sounds as an QS8. Too much stuff in such a small unit, the pianosamples sucks. The A90 hs got a great many good reviews, that's all I know. But here is my advice: Try the KORG SG-proX Stagepiano/Masterkeyboard. This one has a great action, unbelievable good piano-samples (app. 12 MB piano-samples) + + .Unfortunately it cannot be upgraded, so U'll need extra sound modules.
yogi