I trying to gather as much info on this wonderful device.
It seems that the ryscc.com has been down for quite some time, and I would like to share my findings. The zip files contains the last known (afaik) firmware update for the proxmark pro kit, which I was able to retrieve via wayback machine. You can find the guide here, in pdf format, as well.

I would like to add, for safety reasons, please scan the files. If anything is found please message me and I'll remove them.
As I mentioned before, I downloaded these off a saved page on archive.org, but one can never know.
ProxmarkPro_Client_and_Firmware_v1.1.zip
ProxmarkPro_User_Guide.pdf

Thanks to Iceman for picking up after the original repo went stale. Here's a link to his fork.
https://github.com/RfidResearchGroup/proxmark3

At this moment, I'm not sure if any binaries compiled with that fork will work with proxmark pro. I'll have to compare the last binaries provided with the other proxmark versions with the proxmarkpro's. Hopefully, with time, we'll be able to merge all this into one project.