I agree with C-Bears. My FP heats the downstairs, especially the living room pretty well as long as the outside temp is in the upper forties or fifties and the inside temp is in the fifties or sixties. Colder than that, I use the furnace, usually in addition to the FP.
Also agree with NC Hauler, my FP weighs maybe 15 pounds. So the weight argument doesn't make much sense. As far as space goes, even if I removed mine, the space behind it would be negligible. My TV retracts down behind the FP. At most I might be able to get some very narrow shelves in there, but it would not appreciably increase my storage space.
My FP stays right where it is and I will continue to enjoy it, both for the heat it does produce and the ambiance as well.