Fewer moving parts and no reciprocating mass, but aren't they infamous for wearing out rotor seals (apex seals) in double quick time, leading to loss of compression and the tell-tale ton of black and blue smoke out the back? They're also not the most economical, but that's a separate issue I suppose.
I like the look of those Cosmos. It's a 'unique' choice that you don't see around that often.
I think almost every car that's interesting has its weak points though. Go with what you want!
Last edited by God_speed; 01-17-2013 at 08:51 PM.