I did a little side by side when I briefly had both. The Red Ripper can get close to The Prunes sound, but the prunes is wilder and squelchier (for want of a better term) it is far more synthy. The Red Ripper can do a whole lot more as it can cop big muff sounds as well as sounding like a brassmaster, it's all to do with the RIP control. I sold the prunes to get a 5 string Yamaha, then bought the red ripper, and once again sold it to get other things. I did compare with some fuzz/filter settings on the C4 which were close enough to make selling them easier.
I do wish I had the disposable income to just keep things 😂