I like them, but I wouldn't use them as my main tone.
To me, though, a "traditional" standard P90 is like 85% PAF tone mixed with about 15% hot Tele-ish tone. And even though PAF's can be cool for metal, they're certainly not a "traditional" Metal sound anymore from like the 80's and on. And Tele... well, people get them to work, but they get you a very niche Metal sound in themselves.
I bet that if people explored, say, like a 16K overwound P90 with dual oversized Ceramic magnets and hex polepieces, it would KILL, but at the same time, that would only sell on a very niche market.
I have a Duncan Quarter Pound in my Esquire, and it sounds surprisingly heavy, and it can do a pretty passable impersonation of a Metal humbucker when set right. Would it be my first choice if I wanted to record a whole album? Probably not, but it's fun to mess around with different tones from time to time.
And about the noise... I would get a noise gate if you wanted to comit to P90's and single coils. The Decimator, the Sentry, and the HX's noise gates handle the noise from the Quarter Pound no problem, and I don't have to set it any differently than I do with my usual humbuckers, even.