Regarding the SIT amps and high impedance loads. I tried out a SIT2 with my Coincident Super Eclipse III speakers (14 ohm nominal, 10 ohm minimum) and Nelson Pass had me buy a couple different resistors to add across the speaker terminals in order to increase the load. He said that the SIT2 would sound a little dry and clinical when coasting on those easier loads and would warm up if I added some additional resistance. Apparently using different resistor values was equivalent to using the manual adjustment knob on the SIT1s. I just bring this up because I think Nelson made the amps with a nominal 8 ohm load in mind (or at least something below the SEIII's 14).
If I were you, I'd consider e-mailing or calling Pass for a few speaker suggestions. Probably no-one knows as well what speaker will excel on your amps, and both Nelson and Kent English at Pass are always super nice and happy to provide input. Personally, I think it would be a disservice to your search not to find out what they suggest.