I think the 390 is a good saw in the role for which it was designed, and that's as a large homeowner's saw. I owned a 310, and have run an 029 quite a bit, and I think this series of saw gets the job done with a good amount of reliability and enough power to get most jobs done. Where they fall short is on their power to weight ratio, and a shortness of power when it comes to long bars or timber applications. It's not a professional saw by design, but it doesn't mean it can't be used as such. It would just be too much saw to lug around and you'd be far better off with the 361 for the same power, and a 44 or 46 for larger work.
Jeff