I can't imagine gigging a Champ 600.... I wouldn't worry about my 600 overheating.
I think it's a nice little amp.
I bought mine about 4 years ago. I upgraded the speaker to a Jensen MOD. I have before and after videos on YouTube.
I have had no problems.
I like the tone a lot. It's warm with articulate highs and enough bass. For the $149 that I paid I think it's very nice for clean noodling at night. I have a few low power tube amps. I mix playing them all so I don't play the 600 every night but when I do play it I enjoy the tone and feel.
It's a cute little Fender tube amp for the price of a good pedal. It's fun. It's all good.
It takes an overdrive pedal and a tremolo pedal very well.
Nice little amp.
"The rock and roll business is pretty absurd, but the world of serious music is much worse." - Frank Zappa