Ryriken,
I went from a pair of Merlin TSM-mmi's to my current De Capo's, so it's a question I can speak to.
The Merlin is a very mature and very refined design. Bobby Palkovic is a first-class human being who gives world-class service to his customers.
That said, the De Capo's, in my system, are making me very happy. They are imaging "monsters" and throw an enormous soundstage if the material warrants it. The midrange is beautiful, highs are sweet and extended and not harsh (especially with the new tweeter) and there is enough bottom end (I think they are rated down to 42 Hz) that orchestral music and bass heavy rock 'n roll have good authority and I feel no need for a subwoofer.
Also, in my system, they paint a coherent sonic picture of the performance that I find involving and intoxicating. It is very, very hard to describe in words exactly what these speakers get so right, but the result can be a level of emotional, musical communication that is quite wonderful. They are bringing me a lot of pleasure.