I tend to like hardshell all around. That said, I'm using a Gator bag with my Pa1XPro and haven't experienced any problems. Then again I don't toss the thing around (that's Tarzan territory, anyway).

I've hung on to my old SKB hardshell (the Pa1XPro doesn't fit inside it) for when the Pa900 turns up at some future date. Anyway, if the closest fit you can find for any keyboard isn't quite snug enough, it's cheap enough to add a few blocks of foam.