Can the KEF LS50 rock?

I have had a ton of monitors through my system in the past 10 years and the LS50's were my least favorite, notwithstanding their fine reviews.  I found them to be harsh and very hard to drive.  I have fallen in love with Dali monitors, very neutral in their sound.  I have a REL T7 sub that fills out the LF very well with my current OB speakers.  I think some of the best monitors around are offered by Fritz Audio and would suggest you consider a demo of them.  No question that ELAC floor standers ought to be on your radar, particularly at their price point. 
Good luck, Whitestix

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

Hey johnnyb53. I know the Elacs are getting great reviews but I don't know if I want to invest in a pair of speakers featuring "luxurious textured vinyl finish."

Music Direct is also selling the Wharfedale Jade 5s for about 600 more. I do like wharfedales.

To me, Bob made the really relevant comment early on:

"The LS50 begs to be high passed" (maybe low-cut would be clearer).

The speaker looks great with smooth (and very gently falling off-axis) frequency response.  However, it can't produce really clean output below 200hz and is a mess at 100hz - provided that the power in/SPL in the test is reflective of that in actual use - which is, in turn, dependent on any individual listener's preference in a given installation.

IMO, if you're using this speaker for listening to wide-bandwidth program material at real world SPL, a high quality, actively crossed sub-woofer will almost certainly produce a tremendous improvement in bass response.  I'm not sure whether I'd cross at 100hz, 200hz, or somewhere in-between, but I'd definitely add a subwoofer (or two in stereo) for this type of listening with the LS50.