I have have had two, and currently have one. Yes, I have found, based on the two that I have had they do in fact blow rectifier tubes very easily. The first one I bought, about a year and half ago, was new from a dealer. Within about 6 weeks, it blew four or five rectifiers, plus the fuses. I took the amp back, they took it a part and could find absolutely nothing wrong with it. I returned it for a refund as the problem woulld not go away. Fast forward several months and I was really missing the tone form it - it really is an amazing sounding amp with either a Tele, Strat or LP. Over that time I picked up a Swart AST 112, a great hand wired amp out of North Carolina. Great amp, but I just didn't care for the tone in the clean channel with my LP. So I decided to take another chance on a LSS. I managed to find a used one that was only about a month old in as new condition, so I took my chances. Sure enough, with a week, it blew the rectifier (and the fuse). I callled up the previous owner and he told me that he was not running Mesa branded tubes in it and had put the stock Mesa tubes in it for the sale.
I decided to go to the store where he bought it (not the same as the one I bought my first). I went straight to the tech department and they told me that the Chinese made 5Y3 was junk, and that it likely was reacting to switiching betweeen the different wattages. They advised two things: 1, put it into standby first before switiching watagges, and 2nd, and proabably more important, use the Sovtek 5Y3. I mentioned to them that if there is a problem with the amp during the warranty period and it was related to a non-branded Mesa tude that the warranty would be void. They told me not to worry about it, that the store would honor the warranty, and that nothing would happen anyways. I think it was March that I got the currrent LSS, use it every day, usualy between 5 and 15 watts and not a single tube blown. It truely is an amazing sounding amp. BTW, if you get it, you'll need to turn down the bass and midrange for any of the big three quitars (especially the LP), it's bass and mid heavy, but the controls work very well. For me, it beat out the Swart AST Master and my stock 75' Fender PR (one of the holy grails of clean). It's a very repsonsive amp, and the clean channel is unbelievabley rich and harmonic. The drive channel obviously does quite a bit, but if you want to dial in just enough for a classic blues, or Texas blues break-up, no problem. In a couple of weeks I'm going have the chance to compare it to a Swart STR Tweed and a Carr Sportsman. I look forward to that. Best of luck