Just to satisfy the curiosity of a nosy European, under what category (if any) in the USA could one fly the likes of Steve's 14% scale DH Comet (weight 120 lb wet, pair of P-120 engines) or Dave's Vulcan (150 lb wet, pair of 36 lb Merlins)?
In other words, is the 75 lb (jet) 100 lb (prop) an absolute top limit or just the start of "Experimental".?

It Britain, anything over 20 kg (44 pounds) needs to be inspected and certified similar to your experimental class.