Well, I got everything copied over and updated in the R8.1 folder and everything was working great until I launched VR mode. It is choppy as hell (I run a 3070 on a i7-11700 so there is no excuse for any chop - it runs 100+ fps at full graphics with R5). I spent 2 hours trying to figure out why with no luck. So, back to R5 I go. Also, R8.1 was doing weird things with some of my non-pack hair mods, like forcing them to be a grey color. Couldn't figure that one out either.
The only changes I like from R5 to any of the newer packs are the "random" buttons for body parts, skins, and clothing. If I could pinpoint what mod or plugin is doing that I would just install that.