In theory it could work, but even if it does, I think you will be much happier with a real 32P or 64. The 32P is hardlocked to use channels 10-16 (the PCM slot = channel 10 iirc). But U110 can use channels 1-16, and will have to be manually arranged to match. Also the 32P has more internal instruments than a U110 does, so you will need to have the right combination of cards in the other 3 slots. I have no idea on sysex compatibility though. I don't recommend this idea. Some times it's best just to spend more money and get what you want. The 32P sounds great in my opinion, and it blends well with the 32L.

There are around a dozen or so X68000 games that use the 32P.
Plus a few more on FM Towns (Xak III) and probably some on PC-98.
Besides Gemini Wing, the X68000 game Choujin also supports the expansion cards.
There are also some demo music tracks that do as well, which were part of the NAGDRV set.

Oh, I thought they had the same 64 sounds. It was not about saving, but on the contrary, I hoped for a better solution without having to change cards. I would set the channels firmly in MOTU MIDI Express. But it's probably not really worth it and I'll choose CM-64. Thank you.

Thinking back now, I had a friend try this about 10 years ago on his x68k and it just didnt work.