While your idea does have some merit, at the moment Amtrak doesn't have any Metroliner FC cars to spare. I believe that there are only 12 of those cars left in service at this time. At least three, maybe four, of those cars are currently servicing the Downeaster's Business Class. The rest have been pressed back into regular Metroliner service for the NEC, due to the Acela Express problems. Currently I think that there are 6 Metroliners per day each way between DC and NYP. So that pretty much uses up all available cars.
That said however, if and when those cars become available, it might not be a bad idea. The chairs are indeed wider and more comfortable, plus in addition to a footrest they also come with a calf rest just like a recliner. That's a feature that I miss on the new Acela's. When traveling long distances, it makes your trip far more comfortable. Plus you still have a food service area in the car, which could be used for the BC passengers only. This would ease the strain on the regular cafe car, while giving the BC passengers an extra perk. With Amtrak trying to boast business travel between Tampa and Miami, something that they've been trying to do lately, this could be a real help.
I would even say that if they are ever return the sleeper to the Palm/Palmetto that they should keep the Metroliner FC cars as BC cars on this train. That again assumes that Amtrak can ever spare the Metroliner cars and finds a sleeper for the Palm again.
