I've also been a full time sound guy in years past, and still do the duty on occasion. I'm not unfamiliar with the crusty and "quick" attitude that can be given to musicians at the hands of a stressed out sound tech, and understand - but do not necessarily justify - the behavior when it is exhibited.
Now all that said, I'm a pretty reasonable guy, and If I, as a sound tech, were presented with a bassist in a band, that is one of many bands on a billing, and with a lot of sound checks to take care of, my first question would be "what am I going to get from your dual amp, dual mic'd rig that is absolutely going to make you and your band sound better than a DI solution?". And the bassist had better have some really good answers. I would also listen to the bassist's sound, and if I thought that I couldn't replicate that tone through the PA system in a meaningful way using the tools at my disposal, I MIGHT indulge said bassist in his 2 mic summed to mono feed to the mains. But if this approach wasn't working well and caused more problems than it solved, I'd be back at square one with the bassist, and again, if many bands/soundchecks waiting, I'd have a very short leash time-wise to indulge him UNLESS this specific bass player had established bona fides in the local musical community on some level.
I've asked the questions of the OP, to disclose more about the venues, stages, PA systems, number of acts, etc., in order to get a better idea as to whether he's making much ado about nothing, or whether his method would actually bear good fruit. If the OP is one of many bands doing a 40 min (or less) set length, and is performing in a room where the stage volume of many instruments (guitars, bass) will mostly cover the room and only need minimal reinforcement from the PA system, then his efforts may just be effectively a bunch of pissing in the wind, and the efforts with respect to FOH issues will not be appreciated in the audience.
If the OP is performing as the the sole, or one of two acts on a bill, with substantially long performance set(s), and in rooms that absolutely rely on sound reinforcement for audience coverage, then the OP will stand a better chance that his mic'd dual amp rigs will be translated via the FOH.
My 2 cents is to avoid the reliance on microphones and use a mono-summed wired solution via direct boxes, stomps, or some other unit that has cabinet emulation built in, ideally that replicate the cabinets being used in the OP's stage rig, but at the very least offer the EQ filtering characteristics that would allow the intended stage tones to be replicated (even if generally) via the PA system. FWIW, in large rooms, I have rarely heard a bass guitar's stage tone accurately replicated via the FOH sound system. Too often you hear all "sub woof" with very little clarity in the mids and highs. And it seems that the larger the venue (concert) the sheer volume of the FOH system makes so much of what the bassist sounds like an unintelligible ball of glop. (There are other threads on this topic). JMHO
