I just spent three hours repotting the plant, and I'm pretty happy with the results.
It really was 90% roots. I think there was maybe two cups of potting material left in it, as I found in the base it was being broken down by springtails into bug-poo looking pellets. I didn't even know it had them! I knew my NoID African violet had them, but it has had 0 contact with that plant which is halfway across the room by itself, so I guess it had its own infestation when I got it. At least they're harmless. I think most of my time was spent trying to remove the bark that had been trapped in the roots higher up in the pot which were super compacted together -- I don't want more springtails, so all the old stuff I could get out had to leave. Going to do similarly for the violet tomorrow.
I ended up with 3 plants because of the way it was growing -- the main plant which is still 6ish pbulb, one with two giant pbulbs and new growth, and one much-smaller-than-ideal one that has a new pbulb almost the size of the one it was growing off of. Of course it had to be basically impossible to make two equal divisions. I think the rhizome was basically making a 3 shape or a euro or something, but there were so many roots it was hard to tell what the heck was going on beyond the edge. The two small plants were basically ones that were wobbling around excessively and/or off by themselves interfering with my ability to repot the plant in a logical fashion. I did remove about 4 old pbulbs that were significantly smaller than everything else and not really adding anything to the plant. The main plant I think has two new growth areas so I'll still likely see about splitting the big plant in half once it needs repotting again. Maybe it will be more cooperative if it only has 2 main new growth points instead of 4. It'll be interesting to see if the little guys survive. Obviously I don't think they're going to be blooming any time soon, but as long as I still have 1+ plant, I'm okay with whatever happens.
And a pic of my grow area just for kicks.
Still will likely have to adjust plant/light height for everything at some point. Just don't mind the emo rex begonia, I watered it after taking the pic, heh. I can't believe how dramatic those rexes are about watering -- its lower leaves are probably 4 inches higher than that pic now that its had a drink. I still have 3 other plants to move into that area once I figure out how to space them. I know at least for my phal I'm waiting until it finishes blooming before shuffling it over to the light.