I tend to believe Irish Jet Driver re RVSM. The elderly 146's we had in Citiexpress were limited to FL260 even on MAN-FRA and INV-LGW, probably because it was dangerous to fly them any higher lol. Mind you the most basic of machines G-MABR proved her worth many times over.
I thought the hairdryers would prove useless above FL260, then what do you expect from engines that worked better on helicopters...
And that brings me to the E145 that although limited to FL370 hit FL390 to clear the top of a CB and was briefly grounded on arrival for checks. No doubt there's redundancy built in all of these.