For what your after and based on options you presented I'd suggest the ROV. That comes with a few caveats though. neither the f50 nor the ROV are going to be quite as tight as you want, so get a decent EQ. If your a wuss about messing with such things, the MXR KFK Eq pedal is an option, I personally own, and swear by a real PA EQ. I have a Rane ME60 which is a 2 channel, 30 band EQ. (guitar -> volume pedal -> morley ABY with A going to my F50 head with a choralflange which is my clean sound, and b going to a zvex superhardon which feeds both channels of the rane which then feed my stiletto and my JCM800 which is my dirty tone). the 30 band EQ has enough range that I can EQ exactly the sound I want (and even boost the overall signal transparently) and take care of the stiletto series I's well documented and much lamented lack of gain and tightness. Personally, for the kind of metal tone your after, the mark IV will serve you a lot better, its got tons of gain, and is super tight, so you'll be able to simplify your rig somewhat compared to what I use for my dirty sound.......but if you have a rectoverb, an EQ + hotplate will get you what you want
my 2 cents worth
