I would say that the emulaton is very accurate. I haven't A-B tested against the Fender amps like they did in the NAMM videos but I have tested against the Pod XT emulation and much prefer the FDR and FBM. I've tested a lot of COSM devices and these are the most accurate I've tried so far.
My opinion is that FBM-1 is very close to the real Bassmans Iīve tested, but the pedal has more dirt when cranked (not a bad thing). FDR-1 is also close but I think the reverb sucks a bit. When using these pedals itīs very important to use a clean amp with good headroom and quite a bit of volume. I think they sound better in tube amps, as the tubes warms up the digital stuff (or something...), but I have used them with solid states amps with good result. I like both of them very much and I suppose they are going to be very collectable in a couple of years, I have a suspicion/feeling that Fender will stop the collaboration after a while. No reason for this but I have a feeling....
I think that they will collaborate as long as sales stay robust. They come with a fairly high price tag, one that could make a fair down payment on a real fender twin for some one who doesn't have a tube amp already.
Guitar World and Guitar Player magazines both gave pretty positive reviews of both pedals over the last couple of months. Some good info in each review.