This represents only my opinion so take it for what it's worth...
You know - I was somewhat concerned about the "repairability" of the Monocoque chassis as well. However - I think the aircraft industry has proven that alloy monocoques are not only safer from the perspective of energy absorbsion & distribution but also repairable.. Now - that doesn't mean you're going to be able to take your RCR (or any monocoque) to just any body shop to have them repair the tub, but there are more and more body shops everyday that are becoming alloy and composite capable just to keep up with some of the new machines being sold..
Now - don't take what I said as a negative toward spaceframes. Not the case at all. Spaceframes are more easily repaired but have more of a tendancy to "telegraph" energy to areas that you'd not expect.. For instance - a head on hit to a ladder chassis on one of the two main frame rails will quite regularly "Z" the chassis - many times to the extent that repair is not feasible.
Depending on construction methods - the Semi Monocoque will/should be more rigid than a spaceframe which can bring together some of the best (strength) and worst (repairability) of both the full monocoque and Space Frame qualities..
If you take a look at the RCR tub, you'd find that much of the tub is a full .250" thick. What isn't that thick - I've measured at .187" (3/16) thick... The welding is absolutely superb and with very good penetration.
To see one in person will definately give you a very nice warm feeling...
Matter of fact - I had to check to see if I had wet myself!
