Shim,
1. Only your ears and heart will decide that.
2. I believe Korg is as easy in live use, now having the PA800 for a while.
3. Setups are very different, but easy enough in both cases.
4. Third party support (help, styles, etc) - hands down, Yamaha is the clear winner.
zuki
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Live: Korg PA4X/Zed 6FX/EV Everse 8s/Senn 935/K&M stand
Studio: Korg PA4X/Yamaha DGX670/Yamaha PSR SX900/Boss BR900CD/Tascam DP24SD/MTM Iloud/Senn 935/K&M stand/Shure SM57/Sony C80 (2)/Blue Encore 300