I am only familiar with Dali in the stereo realm, and not HT. I own the Epicon 6’s and am very pleased with them. I like them well enough that I will consider Dali speakers for a HT room that will be built in my next home. They are very balanced, as @audiotroy stated above. Non-fatiguing, very musical, with sweet mids and highs that you can listen to for hours. Soundstage and imaging are fantastic (at least as I have, driven by monoblocks) That said, they miss a little bit of detail in the highs compared to, say, B&W’s sound.
I mainly listen to small acoustic ensembles, folk/rock, jazz, and electronica. They excel for these genres. The Dali’s would not be my first choice if I listened to metal or grunge.
The bass is both powerful and precise. I do augment with subs (2 Rythmik F12G’s with active crossover) which are placed so as to tame room modes. As a side effect, it also gives me the octave from 20-40Hz, important in electronic music but not so much in some other genres. I’ve not heard the Dali sub, but given the quality of their product line, I would imagine it plays quite nicely with their speakers.
I find they are great for low-level listening as well as mid volume (I don’t listen loud), and they sound good off axis as well, so your "sweet spot" doesn’t have to be just 12" wide.