I ran into an interesting need on bass for church yesterday and the Rumble was spot on. No lead guitarist and they needed this particular line--but bass at same time. I was able to tap the guitar line....but where the Rumble shined was in an area that normally doesn't work well with the active Bongo bass: Overdrive.
I used an EHX Bass Clone--a touch of overdrive--and with just tapping got a convincing lead guitar line while laying bass with a tapping left hand. The Bass Clone has a crossover where the low bass signal doesn't get effects. Glorious. I had another bass player in the congregation swear that I am a genius---but no--just really good equipment....and balls to do something stupid. Even a blind squirrel finds a nut from time to time.
If you tapped out a guitar solo while holding down a bass line with the other hand, you sir, are a genius.
I can't even scratch my nuts with one hand, and... well.... basically, focus on anything else, at the same time.