FWIW... I have no idea what the price of a PCM-91 or used 224XL is so this suggestion may be way overbudget... I've been exceptionally happy with
the Kurzweil KSP-8 w/ the RSP-8 remote [goes for $3,250]... mine is set up so I have 4 mono inputs with 4 stereo outputs. I generally set up some kind of "hall" like reverb on engine 1, a "plate" like reverb on engine 2, a kinda "leslie"ish effect on engine 3, and whatever else the song might need on engine 4.
The 224XL IMNTLBFHO was the beginning of the end of Lexicon reverbs. They got the constant density plate really good in the 224X, but it got very whimpy and thin with the 224XL... from there it seemed to me that the overall quality of their reverbs suffered as each new model was released.
I have not used
the PCM-91 so I can't actually speak from experience with the unit, but if it's anything close to the algorithms used in the 960L, it gets a great big "not worth the bother" from this user.
Realize that the only reason our shop pimps the Kurzweil unit is because I'm a hardcore user of the thing... it's the only "multi-effects" unit in our studio. We have a bunch of other dedicated delay lines, MXR phasers, MXR flangers, Lofts, etc... but the KSP-8 is the only modern multi-effects box I've used where I thought the reverb sounds were good enough for use on my projects.
I've tried
the 960L, I've tried the "Orville", and I grew up around the other Lexicon stuff [the first digital reverb I ever used was an original 224 in like 1979!!]... for my money, the KSP-8 does "plate" reverbs better than just about anything... with the possible exception of the old EMT-250 which has a tone to it that is just out of this world.
Best of luck with your search.