I now have the same A Data 32GB CF card that Jeff has, and I can also report a success with a previously Rockboxed H120 as well. This is really a great mod. I've modded this player once before with a 40GB Toshiba replacement HDD, but it was a used drive and died pretty quickly. This looks like a much more promising solution, and still 12GB more than I started with.
When I bent back the jumper pins on the adapter, the jumper appeared to be loose, but I think that's just because the part that holds it in place more firmly is at the top of the jumper - I turned it upside-down and fit it into place, and it looked like it was holding on fine.
I'm not really using the H120 as a DAP right now, actually - it's more of a PortableApps device at the moment. But I'll be using it to listen to some language instruction audio pretty soon, so I'll be testing its battery life too.
Thanks to everyone for this mod, it encouraged me to bring this poor beast back from the dead. Again!