They're actually like modded versions of those amps..they don't sound better or worse or even that similar at all. There are quite a few demo's out there that do comparisons & there's always a difference..(whether for better or for worse..that's subjective). For instance the 6262 is significantly less noisy/fizzy than a 5150 or whatever they're called now. It also has less bass.
Personally the 5150 sound is something I'm not nuts about anyway & every other band these days uses them and sounds the same so if it was me, I would'nt get either lol.
The 333XL is exactly what I want in in an amp tone-wise. And as I mentioned before it's been totally reliable..have'nt even had to change tubes (maybe thanks to the "infinium" thing..)