My impression is that the Denafrips DACs are a little warmer, smoother, more musical sounding than any of the Bel Canto stuff I have tried. But I haven't actually heard the 3.7 so that isn't very helpful. Other Bel Canto models always struck me as being mostly neutral with just a hint of warmth, and Denafrips seems to go further in that direction.
I've tried most of the Denafrips lineup and feel the Pontus is the sweet spot for value. Definitely try one in your system if you can arrange for it.