I hadn’t heard that - although I’d be happy if it were true! I sliced the sidewall of my RR on a sharp rock not long after I bought it. Very annoying, but I patched it on both sides and it hasn’t caused any trouble since. The sidewalls are extremely thin though, like a road tyre (which is how they get the weight so low), so a bit of extra strength at the expense of a minimal weight increase would be well worth it IMO.
The RR 2.4 is a superb xc/race tyre for my style of riding (minimal hopping and no big drops). I ran it with a tube at first, but it was getting lots of thorn punctures so I decided to go tubeless with sealant. It’s not the easiest tyre to get inflated in tubeless mode because it’s so thin and floppy, but it gives an excellent ride - I was quite skeptical about tubeless but decided to go for it as I was going to use sealant anyway, and was extremely pleasantly surprised. The main down side to tubeless is it’s not really practical to change tyres often (very messy and wastes the sealant). Suits my race machine very well though.
The RR tread isn’t good in sticky mud because it clogs up and the spikes aren’t long enough, but in any other conditions, wet or dry, it grips really well. Oh, and it’s really light - but you already knew that 
Rob