I use Wharfedales for my mains and center but have not heard the surrounds you have purchased. I almost bought a pair from ebay a short time ago but as I already have in-walls I could not figure out an excuse to pass by the wife.
I am a big fan of what I own (big suprise there) and the other Wharfedale models I have heard. What I would classify as a "warm" sound and not fatiguing. There are other Wharfedale owners here that have the OPUS series so I'm sure you'll hear from them soon.