To be honest I am not sure that a single analog sub can handle both high end two channel audio and home theater equally well. Heck it is hard enough to get mains that will do both jobs to satisfaction but I think the job is easier for mains than for a sub. Frankly I have never had a sub do a better job of filling in those musical passages under my mains than the larger Rels. Now a good deal has to do with the other components of the system. The room size is accomodating as well. I have full range bi-amped speakers for my left and right channels so I am not asking the Rel to do a hell of a lot. I am just asking the Rel to do what I want done extremely well. Also, one's musical taste comes into play.
I do enough home theater that I was not comfortable with the Rel as a home theater sub. There is no question in my mind that I would not like it in that role and have a different sub that I use for home theater. But there again, if you are really going to be picky about this sort of thing, I am not sure that a single sub design is capable of doing both jobs because the tasks required in each case are really not even similar let alone the same. If your room size, other components and viewing and listening habits will allow for it, you can probably find a way to live with what will surely be a compromise. It might really be interesting to see if what sounds like an ability to dynamically alter how the sub actually works (ala Veladyne's DD series) is the ultimate answer to the question. Then again, I may be mis-reading what Veladyne is actually claiming for the DD series but I think I have it right.