Hey Sven . . . I always start with one acoustic kit preset, and drag and drop individual sample drums if needed.
The real power in BFD3 is the Groove Palette, the way you can build a song, and create variations, edit the fills, right inside BFD3 (it also drinks none of your beer) . . . and it syncs perfectly inside Sonar. At some point after an idea is developed enough I usually drag the BFD3 song onto a track in Sonar to take it to the next level.
BFD makes its own drum map in Sonar, no editing of that map has ever been required by me.
Easily edited in PRV, or Staff View (once you set the layout)
It's true, the velocities act differently than some other drum packages, but they have followed a concept of trying to make it respond like a studio mic'd kit would, with all the many microphone interplays, and crossfeeds. As a result, you have total control over every kit piece, the room, and a built in drum mixer, with effects, but the velocities don't always act in a linear fashion because of this. You say you think the samples respond much too linear, I haven't found that to be an issue. I do agree that the different kits are recorded inconsistently . . . that's why I always start with just one acoustic kit, and replace pieces as needed for taste. You just need to find your favourite all round kit for your style, and go from there.
I find BFD3 shines more as an Acoustic drum kit package, than is does for Electronic sounding kits, for that I might try NI Battery or AD2.
BFD3 does take a longer time to figure out, because it's deep with features, unlike some other drum sample software where you're up and running right away.