If you have a pair of these already: you could use the one here for a Center. As surrounds you'd probably be okay - just turn up the volume on the one that's not as loud and you probably won't notice on rear channels. I've personally just been using the subwoofer aspect of them: Dual stereo 10 subs with Kef LS50 Meta's! I used to have a 10 B&W subwoofer - but the dual 10's on this sound better and stereo subs really do help!
The fact it takes up so little floor space is great! Essentially NO floorspace considering you'd need stands for the Kefs! There's some speaker stands that cost more than this! + I doubt you can find two 10 subwoofers this low which take up this little space.
Honestly, I'd say use them as speaker stands + Subs. A pair of LS50 metas or Q150's + these would be a perfect low cost full range setup with little floor space used.
AKA I don't know why one is lower in level/ would recommend just using them as I did: as dual subs + speaker stand. This item is in the category "Consumer Electronics\TV, Video & Home Audio\Home Audio\Home Speakers & Subwoofers". The seller is "mnmusic" and is located in this country: US. This item can be shipped to United States.