just built one of these and just waiting to get the driver (when i can afford it!)
couldn't wait so i fitted a generic chinese driver for some bass reflexes i had kicking around and i must say its very impressive , gives an almighty thump! dont know the t/s parameters of these drivers so i eased the volume up slowly giving the driver around 600watt and it was very controlled (no flapping about)!
so can probs wait for the rcf for a while because these sound pretty good!
very nice plan , seems quite forgiving on driver choice too!