I think that it is very dangerous to wrap the long hose round you in a hog style if you don't dive with others who do the same, and are drilled in donating/recieving air that way.
I would also question the use of a single piece harness without training. If you don't have it adjusted properly it maybe tough to get out of for some. (EG RIB diving) and this can be dangerous.
Obviously for your trained GUE diver these are not issues, and having dived with DIR guys the last 3 years I can assure you of that.
But when talking about "Cherry Picking" one must be mindful that the system could have negative effects if the kit is bought without the training.
In the end I realised that I was being out dived in pretty much every area, and that my kit never seemed to streamlined or effective as my friends. So I changed out all the kit, and booked on a GUE course.
So now I am about to start the GUE-F course, and I notice from the roster of 6 students, I have taught 3 of them to dive! (CMAS *, ** and Nitrox.) How fucking stupid am I going to feel if I don't pass.
Sorry for the tangent, back ontopic:
Anyway I hear lots of people saying it would be tricky to dive "DIR" in their clubs/area as they would be short of buddies. Well I had the opposit situation, all my buddies had changed over.
It's a great system, and whatever your experience/qualifications, diving is all about learning, so take a DIR-F course if you want to "Cherry Pick" you have nothing to lose and you may learn somthing.
Just my 2p.