I think the VTF-1 MK3s would likely be an upgrade over the ProSub 800s, but I think VTF-2 mk5s would be a more significant uprgade. The VTF-1 mk3s do great down to 40 Hz, and good down to 25 Hz. If you are watching movies with deep bass at loud levels, the VTF-1 mk3s might be limiting in a room of that size, but a pair of VTF-2 mk5s would be able to handle that easy. But if this system is for music only, the VTF-1 mk3s are killer and can actually handle a good size room.