I used to own Infinity RS 2Bs and I drove them wth a Perraux 3150 amp. I now own Vandersteen 5A carbons and I'm driving them with the old Perraux and a CAT preamp. Clearly my amp is a weak link by modern standards but the dealer assured me it was "good enough" to consider the speaker. He was right. The sound is awesome and suffers only from sins of omission. Anyway, I'm probably a pretty good match for your question (-;
The Rs 1B versus the 5A is not even close to a fair fight. Nor should it be given when they were designed. Richard Vandersteen has done a lot of innovating since the Rs 1Bs came out. If you are happy with the RS 1Bs you wil be ecstatic with the Vandersteens.
If I recall, the Infinities wanted to be at a certain volume to sound their best. The vandys sound great at any volume and they disappear like mini-monitors. It really suprprised me how good they sound at low volumes; the frequency response stays balanced so there is no need to crank it to get "presence" or low bass. Then again, you can crank it loud enough to drive people out of the room and they still sound great.
The in room bass response is a Vandersteen strength and it was a key attraction for me. You get a powered subwoofer with an 11 band EQ as well as bass countour and bass level. I'm getting smooth, deep and powerful bass reponse despite limited placement options in an 11' x 22' foot room (18" from the short wall). And I don't hear the need for bass traps which is a good thing because my wife hates them. Traps were a must with my VMPS Super Towers.
I became a Vandersteen fan by attending shows and listening to lots of speakers. The 7s consistently sounded great and they weren't making excuses about hotel rooms. When setup by someone that knows the speakers anything from the Quattro woods on up can get amazing response in a wide variety of rooms in a wide variety of speaker positions by tuning the bass response (placement of the speakers or listening position at a node/null excepted). I heard the Coincidents at RMAF but did not seriously consider them because I couldn't put them far enough out into the room.
I suggest you listen the 5A carbons. For 25% more money you get a speaker that is closer to the model 7 than the 5a. The balsa wood midrange is that much of an improvement....the sound is so open, natural and detailed but its not edgy or pushed at you.
