I just looked at the data from my 22 5BW and it has 65 data channels. A lot depends on what you are counting though, probably a dozen of those are related to the functioning of the PDR system itself (SD card perf, CPU load, camera temp, etc.). Also, each tire has 3 channels for tire pressure, tire temp, and TPMS status, so 12 alone there.
The only data channels I missed from my Blackwing compared to the C7 was the suspension movement. My biggest gripe was that some channels were logged at too low a frequency to do what I want.
AFAIK, most of the changes with the gen 2.5 PDR in the '25 5BW are related to the in car experience, which is really slick. I'd love to coach a student and be able to debrief on the data without leaving the air conditioned comfort of the car. If anyone has a PDR file from a '25 5BW, I'm happy to crack it open and see what is different channel-wise.
Hopefully this doesn't get my post nuked, but I've spent a lot of time making educational videos to help folks learn to use the PDR data and make $0 off it (in fact it costs me money). These two videos are where I would start.