Yeah, I suck. What can I tell you? I don't like kick mics on my bass cabs. They sound scooped to me. If you like them, fine. Sorry I offended you.
Yeah, agreed, I'm not one to use a kick mic on a bass cab, though sometimes I'll use a d12 (the old version of a d112, though it doesn't sound very similar!) for a bit of a change.
That said however, I disagree that using a particularly voiced mic on similar sources causes them to compete in the mix, theres so much more going on that that. For a heavily voiced mic like a d112 the chances that they clash will be a little greater but if thats the case then you should change your bass sound a little, tune the kick or eq them apart and they will work fine together!
if we don't have time to try out lots of different mics for a session at the studio we use a neumann u67 for lots of things, room mic for drums, acoustic guitar, vocals, sometimes electric guitar and the voicing of that mic doesn't cause issues in the mix!
I know what you mean though, but I think its more of an issue of general mic choice, not using the same one for lots of stuff!
I sometimes use a subkick for bass, good when you want a huge soft low end, good for when you need real bass on a hip hop or drum and bass track for example. doesn't pick up much in the way of the tone of your bass but it is a nice addition to get some of that artificial low end without resorting to big eq boosts!