I run 24/7 with my 6600 at 4050mhz or around there, average about 4.0ghz i guess with 1.55 vcore, then if i am trying to get some good benches ill crank it up.
Yes condensation is your worst enemy either with these or high power techs. You absolutley have to make sure that you do a good job, if you dont then you will pay the price from a simple computer tripping off line to frying your mobo and or your cpu. Its not too hard to do it and there are countless different techniques to use but this is one area where overkill is usually a good thing.
With the machIIgt I have had condensation twice from bad setups, one was just a small spot of corrosion on one of the resister solder point at the back of the mobo (my own fault I was running without the heater plugged in and didnt have the best seal)
and the other time I had made a alternate mounting method for am2 (my first try) and didnt get a good seal on the mobo, I allmost had water running out of the cpu area but I got lucky and didnt hurt anything. This was my own fault and I fixed the mounting solution after this and ran it for a while with out ever getting condensation again.
Nowadays I take more time to make sure I have a good seal everywhere and I know more what im doing so I know what too look for. Still I have never killed a mobo or cpu with phase (yet