Welcome to the forum, thedigitalvee!
The piano engine inside the CA71 is the same as in the CA91, but you get fewer demo tunes and native sounds (60 vs 80), less amp power (80W vs 110W), and --more importantly-- no resounding acoustic soundboard as an extra "speaker". It does sound somewhat less impressive than a Yamaha CLP270/280 because of the more rudimentary amplification. Still, contrary to Craigen (whose opinion I respect), I am more a Kawai fan myself. I believe that the CA-class pianos are just better musical instruments, closer to an acoustic piano, and a better value for the money. Their strongest point --as compared to Clavinovas-- is their

real, all-wood keyboards[/b] made of one-piece, full-length levers, which make the

feeling[/b] of playing them (any of them, MP8, CA51/71/91) immensely more satisfying than playing on Yamaha's actions. The CLPs all have a GH3 folded two-storey action which is basically some sort of a hoax and a clever illusion of reality as compared to an acoustic piano. This includes the keyboard they dare to call "Natural Wood" on the 280, which is but another GH3 with cosmetic (albeit real) wood inserts on the front parts of the white keys. Not really a different keyboard, only marginally so, and they charge you about $500 for that hoax. If you decide your preference is with Yamaha then it's much wiser to save a bundle and get a CLP270, which is the same piano without the made-up white keys.
Also I must urge you to give the Roland FP-7 a thorough road test before making any decision. This is a serious piano to consider as its price is extremely attractive considering what it gives you. Reviews about it are positive.
Good luck to you! Oh, and by the way, it's true that CA 71/91's polyphony is 192, but Yamaha's CLP280/270's, in all honesty, is not 96, it's 128, which is still acceptable by today's standards.
Regards,
Claude