Here's my .02 for what it's worth. Since my front yard is a lake, I get a chance to do a lot of solo diving. From my own experience, it's generally the tank valves/regulators that get snared most of the time. You could either reach back with a knife (being VERY careful) or shears and cut your way out, OR you did a remove, clear the snag and replace of the scuba unit. Since my back injury, I've been diving side mount doubles. The unexpected plus of doing this is that entanglements happen only occasionally now, and when it does, the valves/regulators are right where I can easily reach them. Clearing the snag off of them is no hassle. Worst case situation - I can un clip the snared tank and then clear it. Plus it gives you a redundancy that I never had in a conventional set up. Side mounting takes a little getting used to, but it really does take care of many of the entanglement issues, which is one of the increased risk factors with solo diving. Note - I'm NOT saying that if you side mount that it's OK to go into entanglement situations, I'm just saying that if you find your way into one, it's much easier to deal with.
Dive Safe,
George
PADI MSDT 33859
Prime Scuba