Energy Take Classic 5.1 speakers

I recently bought the Energy Take Classic 5.1 speaker system mainly because cnet.com recommends it very highly. I replaced old speakers that I had from an Onkyo system purchased 4 years ago which came with 7.1 speakers and a receiver (I replaced the receiver with the Denon AVR 791 sometime back but held on to the speakers till now).

I have two questions:

a) Are the Energy speakers better than the old Onkyo ones even though the Onkyos are bigger in size?

b) Which is the better option: combining the Energy speakers for front, center and surround with two of the old Onkyo for surround back or just use Energy as a 5.1 system ignoring surround back altogether?

My living room is ~ 25ft (Length) by 16 ft (Width). The surround and surround back speakers are next to each other at two ends of my living room (the longer side). It is difficult to have a separate mount or space for the surround backs.

Thanks

Thanks for the reply. My living room is ~ 25ft by 16 ft. The surround and surround back speakers are next to each other at two ends of my living room (the longer side). It is difficult to have a separate mount or space for the surround backs.

Thanks. How do I connect both the Subs? I have a Denon 791 as my receiver. I see one Sub out on the Denon which I have connected to the Energy sub.

Also, will increasing the channel level of the sub help? Currently it is set at +0.5 based on Audyssey MultEQ auto set up.