Bindings are kind of subjective, like most other components of snowboarding. You can definitely feel more board with a Union binding. If you return the 390 Boss, and can wait until next season, then Union has added canting to their line on at least one pair of their bindings.
Saw them but I'm wondering in order to build up the canting they will thicken the base plate padding which will result in the same feel as the 390's. I might give these one more shot and crank up the forward lean to ridiculous and see if that helps. But I'd swear the sole length feels wrong but it's set to Rome's specs. I wish they had more adjustment options for that like Union does.