Theater four π speakers work great with SET amps. And about biamping, it's a good idea. But I am always concerned that the crossover be implemented properly - You need an appropriate filter in front of the amps and you need to make sure and remove reactive components after the amps. To find an "appropriate filter" for a preamp-level crossover is not a trivial task because the response curve of the tweeter circuit is somewhat complex. It's not like rocket science or anything, but we do want a response curve that looks exactly like what is shown here:
Response curve required for compression horn tweeters