I had a 670 that was a beast. I still have 520. Good solid saw.
As mentioned the are set a little lean combined with a long bar from the factory. Keep it sharp or you'll burn it up then blame the saw.
I'd go larger for felling, 3/8 pitch but that's not an anti 590 comment.
The 690? Can't member the model number is the next one up from the 590 is the same saw with some added benefits.