I used to own a F30 and a Rectoverb. I currently own a TR and a Mk5.
While there are differences between an F30 and F50, they share the same preamp so sound relatively similar. The F30 combo had a V30 speaker and EL84's, so it had a bit more mids than the F50 - same overall voicing though. Do either sound like a Recto? Nope. Even in Contour mode, they're still very different. I always felt the F series was a bit of a cross between the Marks and Rectos, but it really has a sound all to its own. Functionality wise, the preamp is very "mark like"; the tone stack is pre-gain, so they have very little affect on overall tone, but about how the amp responds and feels. They're great little amps. The only reason I sold my F30 was to fund a Rectoverb. Kinda regret it.
The RoV tends to be brighter than Duals or Triples (and certainly brighter than a Roadking/Roadster), and IMO harsher at high gain settings compared to my TR. But for recorded tones, a RoV will give you a "recto" sound all day. However, IME at band volumes, the RoV can't keep up. The problem is the power section (50 watts, smaller output tranny); it lacks umph and punch. Again, this is at high gain/metal tones. My old bandmate had a 5150 and it ate my RoV for lunch at band practice. I think a RoV is great for recording, just not so much for live gigs - I was never able to get that "massive" sound with it. I since bought a TR and it destroys everything in a 25 yard radius.
I guess I'm trying to say that it depends on your application. Nothing beats a triple recto for massive, ear bleeding metal tones at band volumes. In a studio situation, a RoV will be fine. The F series are cool in their own right, but not a recto replacement.
