Ch5 needs less voltage in my experience... and I'd wager it also get's higher too. I had two sticks of kreton that did 220 (Dual channel) at tightest timings (5-3-2-2.0, 6-3-2-2.0) at 2.5v, but it is a pain in the rear to work with... It would only clock that high with one of those timings, and get this... It would do one fine and not do the other... then I'd uninstall it and reinstall it and it would reverse, the one that it couldn't do before would run fine now, but the one it could do before got errors. It was some crazy crazy ram.
Ch-5 probably will be better ram if going from 2 to 3 ras to cas doesn't cost much performance-wise... and if you get lucky and can find it's sweet spot (Took me MANY hours across almost a month to find it). It certainly is better at stock voltage... but at the time I didn't have any boards that could do above 220 at tight timings (yes this ram was board limited)... so I couldn't tell you if voltage helps it as much as it does bh5's. But maybe I just got a pair of beaut's... anyhow I'm not buying ch-5 again because I don't trust I'll be lucky enough that my boards sweet spot will match up with the rams sweet spot... bh-5 is just more flexible it seems.