Jim, if you really love your RP91, have you thought about just replacing it with another RP91? Crutchfield still has some for sale in its scratch and dent section for a great price. This player is hard to beat, especially at the Crutchfield price of $255 shipped.
This has frustrated me, too. I still have not found a player that makes me want to upgrade from my RP-91 for these reasons. I sure hope mine does not die before something comparable hits the market. I'm holding out hope for the Momitsu V880N being released soon, even though it lacks DVD-Audio support. I am concerned about build quality with such offbrand equipment, though.
If you watch mostly film-based dvds, the latest silicon image deinterlacer is supposed to be as good, if not better, than the Faroudja...
I'm not so lucky - between anime and Babylon 5, I've got lot of video-based material, and anime needs a quality deinterlacer. My CP72 is dead, the Denon dvd-910 jitters. I'm still contemplating replacements. It's hard to find !
DaveGTP, I'd heartily recommend a Panasonic XP30 Faroudja-based model - I got one on EBAY 9months ago and its been perfect. I compared to the Denon DVD-910/1200 and Mitsubishi DD-8040 at that time and the XP30 had several features those others lacked. There are still a few brand new/unopened XP30 units selling on EBAY - I say grab one.