Surely the argument for RAF MR is based around it being primarily a way to handle ac rescue, which happens to be very good at rescuing folk in wild areas who need assistance.
I may be wrong, but I don't think the civ MR teams have any experience/expertise in handling ac crashes, which is RAF MR responsibility from initial search, cordon and control etc. RAF MR was formed after embarrassing performance at the likes of the Beinn Eighe Lancaster crash, not to look after mountaineers.
Whilst given the right contract and personnel I can accept that SAR is perhaps equally good whether mil or civ, I don't see that volunteer civ MR teams will ever make a serious move towards the requirements of mil air accidents.
Edit:Climebear - your post didn't initially appear as I wrote, I wouldn't have repeated it had I been able to read it