I have experimented with Rollei 80s quite a lot. I found a very satisfying developer: Calbe A 49, diluted 1+1. This developer may to be find hard outside form Germany, so I give you a link to a German shop.- Their English pages are not ready yet.
Please look at the characterisc curve of this combination (notes are in German, sorry):
A 49 is the successor of the Agfa Atomal. I use it since the mid of the seventies.