Single crew IFR is more dangerous than multi-crew. That is obvious and well proven and unfortunately even highly experienced pilots continue to kill themselves whilst flying this way.
I have done flown single crew and multi crew and I know which I prefer. Multi crew flying has so many safety advantages over single pilot ops.
In airline flying you are often told to think of the autopilot as another member of the crew (A cranky and occasionally obstinate member sometimes it seems!). In fact it frees up the PNF to do other duties when it goes in. ie when the PF is handflying, the PNF is monitoring them, but when the AP is in, the PF is monitoring the AP and the PNF whilst keeping a watching brief can get on with paperwork or dealing with the cabin etc.etc. That's CRM, using all the resources available to ensure the flight goes smoothly.
I think single crew IFR should always be done with a serviceable autopilot and I really wouldn't want to do it myself without one. If a 1500hr pilot is seen in this example as experienced, then I must be an old salt by now and I would be very loath to go off on a crappy night in a light twin without some form of back up other than my experience. Too many AAIB reports prove that to me.
Most CRM courses are just about how to work with your fellow crew members, rather than telling you how to operate the machine. Stuff all use to the average air taxi pilot really.