my experience with that pedal was a mixed one.
it was IN NOW WAY a true bypass pedal. even when it was switched off, it boosted and warmed up the signal. in some ways i liked it, in some ways i did not.
I did not use it in very many "high gain" situations, and at that time was using a Fulltone Fulldrive I pedal for overdrive. So I would use a light overdrive with the rotosphere, and by using judicious finger and picking/fingerplucking techniques, I was able to get a decent B-3 type of organ sound out of my rhythm parts.
Korg made a unit that Charlie Hunter used a lot, I think it was A3 or something, footpedal with three switches, that was supposed to be a very good rotary simulator.
Several other companies such as DLS have come out with various rotosimulators. I have not had a chance to test them. But have read good reviews.....
I liked the fast/slow switch on the rotosphere, and the way it would RAMP up and then RAMp down in speed, instead of just instant speed switch.
But it seemed that the H&K Rotosphere made me adjust everything else in my rig to accomodate the tonal change that it enforced upon my tone.
I used it because I HAD to.......I needed that sound badly for that gig.
Another issue with the unit is the SIZE and WEIGHT of it.....it's BIG AND HEAVY. and needs its own AC adapter, which became an issue with some countries and venues if you did not have proper step up/step down adaptors.
It's an interesting unit...but remember.....since it uses TUBES, if you have CRAPPY tubes in it, it will sound not as good as it can. and they come stock with just basic chinese tubes of various brands. I think i replaced mine with some "bugle boy" vintage tubes that I had discovered in an old home organ someone had thrown in the trash.
Keep an eye out for those old home organs.....there are some NICE 12ax7 and EL84 tubes in many of those that are valuable...so if you see one in the trash, or in a thrift store cheap, see what tubes are in it...