Wow, that is so interesting. What you're saying says quite a lot about our personal tastes but I think it also says a lot about equipment synergy. What I hadn't talked about with the 800ne and the Triangle Titus combination was the sweetness of the sound, (the very thing you seem to get from the Rotle and the Concepts) and how vocals and the timbre of certain instruments produce regular hair standing on the back of the neck moments for me when listening so I can only deduce that the synergy between Denon and Triangle is just doing something so right for the sound that I enjoy. It does make me wonder how the Rotel would have performed with the Triangle, on the other hand.
Others as I said insist that Triangle have a bright tweeter but I can assure you, I run a mile from brightness or harshness, and I think those critics are probably going by Triangle speakers of old. What you say about the tone of instruments puts in mind of what others say about the Titus and Comete speakers: that a saxophone sounds like a saxophone, a cymbal sounds like a cymbal and so on. When you say you've got sweetness but maybe a lack of warmth with the Rotel I am a little confused. For me sweetness is warmth, I don't mean fuzziness or bluriness, but an almost palpable human quality to voices or the tactility of instruments (wood of acoustic guitars, metal of brass instruments etc). Maybe I should talk about music choices: I don't really do metal or hard rock, but I do listen to most other things besides. I very much like alternative rock, folk, alt country, 60s and 70s rock, (not an 80s fan with a few notable exceptions) and jazz, particulary Brazilian jazz. I like classical but this is the most hard to reproduce genre in home audio: chamber music works much better than full scale symphony orchestras as with the latter you have to constantly adjust the volume to be able to hear the really quiet passages and turn down the loud ones so as not to p*** off the neighbors.
All in all, I think you're a bit of a tinkerer like me. It's great fun tinkering and if you tinker again with speakers, may I suggest Triangle. I'm going to home trial a pair of Dynaudio Emit 20 for a bit of fun. I bet they won't beat the Titus.
Oh and by the way, did you ever get to hear Concept 30s?