I sure hope that one card towards the back is not really inserted into two slots. Half the card appears to be in one slots and half in the next one over. Or maybe it's just laying in there. Hard to tell. $5999 is way too much for this system. But all the seller needs to find is one idiot...
I also have a Rainbow 100A. And quite a few spare parts. I can make new floppies too. But I was not successful in trying to use Kermit to get files to the machine. I know I did this in the past (but transferring a file from it) capturing a ROM dump for someone.
I too have a Pro-350. With the color monitor. I haven't done much with it as I've never been able to copy stuff to it. The disks are in the weird DEC format that is not compatible with a DOS disk. Wish it had the network card, but it does not. I have a few spare cards that came with it.
I never used to think I would like Emacs. Then I forced myself to learn to use it. Actually developed a major mode to help with searching a document for specific words for work. I don't mind it but on quick edits I still use VI.
I'd be interested to hear how you used xhomer to put files onto your Pro. I downloaded the code. I will later build it on my Linux box. I never knew what this was. I had seen it mentioned but never knew there was a Pro emulator.