I lotta guys talk about 2-Pilot IFR being the remedy to prevent SPIFR mishaps.
The theory is, that when the Captain...who is supposed to be more experienced, capable, and qualified...gets overloaded or forgets something or just plain can't hack it, that the Copilot--who is warming the seat to get experience, i.e., that's why he/she was hired for Copilot, is gonna save the day?
The theory kinda falls apart there, you see?
The SPIFR thing is perfectly manageable...especially because it's not flown "in all kinds of weather," like *you* say, but really in pretty benign kind of sorta-less-than-vfr weather. And 2 pilots are not necessary or required, because the SPIFR aircraft is *designed* and *certified* to be operated VFR or IFR by one pilot.
2 pilots are not therefore necessary, plus, that's gonna add 200 pounds or so to the TOGW, and there goes your fuel load and therefore your IFR capability. Oh, you could go the an S-76 as a baseline HAA aircraft, I guess...in a capitalist economy that is not gonna happen. In fact the future is probably all-VFR, with 206's...or drones with no human pilots altogether...but that's another rant altogether...
In the airlines, they use big, strong jets which are gonna go despite ground icing, icing upstairs, thunderstorms, fog down to the ground...Cat III ILS capability, autoland...and all of these conditions are gonna ground SPIFR helicopters. I don't know a single guy now or in the past flying SPIFR helicopters in those conditions.
SPIFR guys don't fly in the extremes. and yet and yet they manage to screw the pooch.
Like the guy in England who was trying to scud run an IFR twin through London and hit a building. Or the 2-man crew of the rich guy who tried to make a 0/0 ITO out of a field by the mansion in the middle of the night and got about 100 yards before they nosed it in. And of course the guy who flew the VFR Astar into the fog from a scene and even though it had an autopilot, he made a hole with it.
The guys who think 2-Pilot IFR is the remedy won't admit it and can't see it, but the problem is not the complexity of the operation but the dismal ineptitude and inaptitude of the folks attempting to do it and then managing to screw up in the most benign circumstances and the most docile environments.
In fact the situation it is so bad that i can cite you a big twin with *two* pilots...like you want...who were advertised to be both of them competent who bored a hole on a milk run.
And the Canadians who did the same thing in that same type aircraft who plowed it in doing a Night VFR takeoff. Apparently the second pilot just sat there and watched, or that's what it amounted to.
It's not the job that's the problem, it's the guys attempting to do the job, and not being able to hack it. Get better workmen, and the job will go smooth...keep on like we're going, and we'll keep on like we're going.
The way things are, the most compelling reason not to go dual pilot is this: it'll save another life when some guy trying to hack it without the capabilities, without the training, and without the experience plows in.
One less on board = one less fatality. It comes down to that.