I would not get too worried about matching your surrounds to your front/center units. If you plan on running music in evenly distributed 5.0/5.1/7.0/7.1 than I can see it but for HT the rears can easily be different. I personally can't tell. As for the sub I can vouch that the fathoms are fine units with way more LFE than folks generally expect from a smaller unit. I have a single F112 in a 12x14 room and its good for me. I think your question about your sub in 2.1 as well as 7.1 will depend your electronics. Lots of experts here but I think it may depend on your receiver and how you integrate with your players and amps?