Indeed, the RCA tubes were amazing but haven't been manufactured in decades. Collins pushed the hell out of 811As in the 30L-1, knowing full well they were doing that, and the tubes rarely failed...but they were American-made RCA tubes.
Those "NOS" RCA 811As from the 60s and 70s sell for higher prices than brand new 2012-vintage Chinese tubes do, when you can find them.
I wouldn't want anything with 811As in it today. Even Ameritron gladly admits they're all a roll of the dice, and although they try to weed out bad ones at the factory, they don't operate them for long and some are still guaranteed to fail prematurely, even without any cockpit error.
The "RF Parts" brand 3-500ZGs (Chinese) seem to be quite good. I've been using a couple of them for years now, and no problems thus far. I suspect RFP simply weeds out bad ones before they ship them, and eats that cost.
A government which robs Peter to pay Paul can always depend on the support of Paul.
-- George Bernard Shaw