I believe the Nekton Pilot only began doing the Belize trip about 6 or 8 months ago, so not too many people have done it. I'd suggest posting on dive sites, of which there are a bazillion, not general Belize sites, for the best chance of getting personal experience reports.
I've heard only that the Nekton Pilot is not as spiffy as the two other liveaboards doing Belize.
--Lan Sluder
Belize First Magazine
http://www.turq.com/belizefirst/