I’m a Reaper fan, too. I use it primarily on Windows, but out of interest just checked with it on Ubuntu and there are no midi device identifiers of any kind to be seen. It just lists Midi Input 1, 2, 3 … 62. (And that machine only has one device attached at the moment.) It’s obviously a work in progress and I don’t really trust it.
Of course, on Windows device identification is much more usable but I do have a vague memory of having to disable and reenable existing devices after adding other kit, presumably because the underlying USB IDs had moved. Checking all this out would be another rabbit hole, please don’t tempt me … 
Broadly speaking, yes. There’s a timing loop in the Erlang code which fires every five seconds checking for new devices attached and this coincided with the glitches. The volume of data it retrieves from sp_midi seemed to be the root of the problem. My final post in that thread has the details. A couple of members of the core team posted to say they had picked up the problem and I’m happy to wait and see what they come up with. In the mean time I’ve turned off that bit of code, too, as I’m not changing my hardware and I have all the relevant identifiers in a text file. The rest of SPi’s midi sequencing doesn’t seem any the worse for this.