karstdvr:
If in an emergency ie entanglement or deploy regulator in a OOA situation does the cable tie fail easily,or can the #24 line but removed fast enough. The downside to cave line is that it involves an extra step which is deploying a knife,and in the case of a spg possibly having to cut where you can't see,which could mean cutting a hose or dry suit.
For OOA, you always donate the reg from your mouth. That reg should never be clipped off, since you are breathing it. The only situation where someone would need to donate a clipped-off reg is with a rebreather, and that action is pretty far down the list of "what to do" in an OOA emergency.
Regarding the SPG - I've never had to do it, but I'm fairly confident that I could cut my SPG loose without looking at it, and without cutting anything else. And don't forget about getting help from your buddy - it's possible that he or she could free it, even when you can't (depends on the situation I know, but it is still a viable option).
karstdvr:
The one thing I did like and borrowed is when the WKPP recommended the use of o-rings,and they work quite well.
I used those for a time as well. I never had a failure in the water, but they do become brittle and cracked over time, even in fresh water. I imagine that salt water is much harder on them. I always replaced mine before that became a problem.
The advantages of cave line over O-rings (other than a stronger connection) is that field repairs are pretty easy, requiring only a lighter and knife or scissors (and in a pinch you can even do without the lighter). I always have a knife and cave line with me (on my spool or reel), so repair is a snap. It can even be done in the water if necessary, which is good if you have to cut something to free it.
With the O-ring method, the second stage or SPG must be removed from the hose to effect a repair, which requires an extra tool or two, as well as a shutdown and purge of the reg. Plus you must have spare O-rings lying around, which means more parts that have you have to purchase and bring to the dive site. Cave line is cheap and plentiful, so it's never a problem getting more when you need it.