Hi!
I have been thinking of removing the full auto burst from bolters (Astartes and RT versions), in order to make them more fluffy (as of p11 of 4ed SM codex, as well as in lexicanum , it is said that they fire only 4 round bursts and that doesn't feel like full auto to me) and to tune them down (so I would make their RoF S/4/- ). As I havent been playing DW yet, how this sounds to you? From my rather short readthrought of the core rulebook, most special talents give bonuses both to bursts and full auto, therefore not making some talents completely obsolete (and they could still be used with storm and heavy bolters.. which is nasty!).
Also I have been thinking to reduce a d10 from all Astartes bolt-weapory damage as after all they fire same type of projectiles at similiar velocities (as bolts are self propelled) than the "civilian" versions. Marines are total monsters in combat, but currently their bolters are just too good (and unfluffy, as they match Tau pulse rifles).