Go with the ELAC floorstanders instead. (Another option is the JBL LSR305/8 + 310s sub in a 2.1 setup, that’s what I have now, super accurate, super awesome, super value)
The LS50 got great resale value though, I sold it in one day for about the same price I bought it at.
I was thinking in the same direction. The Elac Uni-Fi UF5 Tower has a concentric midrange/tweeter (similar to the LS50) but augmented by three small, fast (5-1/2") woofers in a larger enclosure. Their dimensions are very compact, however at 7.87"w x 38"h x 10.75"d. They should match well with your REL even if you don’t high-pass to the Elac towers. They were designed by Andrew Jones and are only $999/pair, meaning you could sell your KEFs and have money left over. They have far more radiating surface than the LS50s, meaning they should be able to "rock out".
http://www.musicdirect.com/p-438083-elac-uni-fi-uf5-tower-speakers-pr.aspx