I bought a diamond X510HDM dual-band vertical, their version of the Comet GP-9, specifically because they claim it could handle 330 W FM on 2 meters, an 250 W FM on 70 CM. I wasn’t going to run quite that much, and quite a bit less power than that immediately fried the little capacitors in the antenna.
To say I was annoyed is an understatement.
?
A friend took the antenna apart and replaced the caps with larger ones, and I have had no problems since. But still, I would be wary of their power-handling specifications.