My dogs love bison. My hubby works at a local store that sells bison (they have a ranch and sell their own meat) and often brings home tidbits from things that he was making (they do their own jerky, sausage, ground meat, etc.).
I'm one of those - there are quite a bit that do this.
Yeah, you shouldn't pour in a scoop of kibble over a chicken back, but I've been feeding a part raw/part kibble diet for several years now and so far I haven't had any problems (which isn't saying much considering it's just one dog). I've heard similar stories though, so that comforts me a little more.
Moreover (as evidenced, ironically, by Jes's dry heaving this morning and the fact that he just puked up bile) his evening raw dinner is long gone by kibble breakfast. The kibble is also gone by the time supper rolls around. The only time I'd be concerned is if you were feeding three times a day - then there'd me some mixing that may cause problems.
I do it because I'm in graduate school and don't have the time nor money to feed an exclusive raw diet. Maybe in the future, but right now (especially since he spends some weekends with the "grandparents") feeding both works best for us.