The PCM-91 will blow the PowerCore reverbs away. I mean that. Actually, even the PCM-81 reverbs handily take those of the PowerCore, for depth, width, and warmth.
I have a PCM-80 and a PowerCore, and while the PowerCore reverbs are a good bit better than just about every non-convolution reverb plug-in I've used or heard, a decent hardware box is still a better sound.
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Current live rig: Roland RD700SX, Hammond XK-3 with Leslie System 21, and Muse Receptor. Also a Nord Stage 76 other times instead. And a Roland FP-7 for jazz gigs.
HOME: Kawai MP8 + a bunch of VI's.