Check out
my site under the Misc section... (yeah, I've a lot of work to do yet on the site). I have floppy images and floppy rips of the driver software for both cards available for download as well as their respective manuals. I've even the drivers available for the hard-to-find 386i memory add-on card (which I'm missing)
These will work in a PC/XT with an 8088 or 8086 processor - you just need to jumper the card appropriately. This means that you can use them to upgrade the IBM PS/2 Model 25, which is an ISA-based PS/2 system, and the main reason that I have these cards (well, that and the low BIN that I found them for!)
For actual reviews of the products, search Google; there are a few in-depth reviews on both cards (mostly from Infoworld, if memory serves)
If you don't have the ribbon cable to run from the card to the CPU socket, you can still order the ends from Jameco and crimp them up yourself.
VCF user Cimvong was attempting to see how far he could push these cards with upgradable CPUs such as the 386->486 chips, etc. I'm not sure how successful he was, but if you use Google to search the forum for his username and sota, I'm sure you'll find the relevant thread.
As far as price, I've only seen them for sale once in the last few years, and that was when I bought them. I paid $40 USD shipped for both cards on a BIN auction. YMMV.