My experience is with the Adox ortho film, which seems to be fairly similar to the Rollei. I really like Diafine for this film in cases where I want high but still more-or-less pictorial contrast; I've seen some *very* nice industrial still-lifes with this combination. The contrast can give a really strong "gritty" impression without the problem of losing detail in the grain.
Originally Posted by pierods
For a more normal pictorial contrast, I've used Caffenol LC+C, since it seems to be the cheapest low-contrast developer in town. Someday (in my Copious Free Time) I mean to mix up a kind of "half-LC" version and see if I can get intermediate levels of contrast.