I don't own any of those subs, but I have a Rythmik F15, not the F15HP (and also a pair of F25s) and two SVS SB13 Ultras. The F15 is not that big or heavy. I have mine in my office system.
No experience with the Paradigm subs, I've never heard one. They make great speakers and the inclusion of ARC in the Paradigm subs is interesting. I tend to think of internet direct as being a better value in most cases than buying through a dealer network, but I could be wrong. I'd be a little concerned that you can't find much info about the Paradigm subs especially if you can't audition one first.
I would also suggest stepping up the Rythmik ladder to an F15HP, since it's about the same price as the Paradigm sub you're considering.
I know you said you don't want to consider anything else, but I think if you can find a used SVS SB13 Ultra you would get more bang for the buck than the SB 3000 and it'll be about the same size.
No experience with the Paradigm subs, I've never heard one. They make great speakers and the inclusion of ARC in the Paradigm subs is interesting. I tend to think of internet direct as being a better value in most cases than buying through a dealer network, but I could be wrong. I'd be a little concerned that you can't find much info about the Paradigm subs especially if you can't audition one first.
I would also suggest stepping up the Rythmik ladder to an F15HP, since it's about the same price as the Paradigm sub you're considering.
I know you said you don't want to consider anything else, but I think if you can find a used SVS SB13 Ultra you would get more bang for the buck than the SB 3000 and it'll be about the same size.