I myself upgraded from the RP-80 straight up the the Boss GT-8! :)
I still have my RP-80 sitting here in it's case not doing anything. When hooking it up to the 8, did you just come out the 'Mono' left output into the RP-80? Or did you figure out a way to run the RP-80 through the effects loop of the 8?
Man, I love these toys! :D
Everything is OK in the end.
If it's not OK, then it's not the end.