Old thread, but my $0.02 . . .
^^^ Yes, what viennadad said.
Why choose between them? I have re-capped, foamed/gooped Model 6s and a pair of restored Genesis Is (from AK'r LeeSonic). The are completely different animals, with the 6s being very relaxed and a little rolled off on the top end and the Genesis brighter up top and more detailed. That Genesis tweeter is special, and the bass is no slouch either, but is no match for the Model 6s. Running them side x side lets you have your cake and eat it too. The Genesis Is pick up on the top end where the 6s leave off, and the 6s give you that nice big, well defined bottom end and over all very smooth sound. Hooked up to low powered cap-coupled receivers, this combo is very sweet!