Steve,
I agree 100% about the commercial braided mono sleeves. I would not trust them at all. Although I know a few knowledgable FFermen theat use them. In my view, they are an accident waiting to happen.
The plastic sleeves are not used with the homemade loops. There are several ways of attaching the sleeve to the line. The method which Dan Blanton uses, is to snake the flyline 6" or so into the mono material. Then secure it with a 10 or 12# mono nail knot over the braid. You could also whip finish it.
Dan Blanton makes the loops just like we used to splice loops in 50# dacron to attach it to a leader or wire. You draw the braided mono inside itself for about 3". Pull the tag end out and form the loop the desired size. Then insert the splicing needle about 3" below where the tag end exits the braid. Snake it up to within an 1/8" from where the first splice ended. Draw the tag end back into the braid core. Trim so tag end doesn't exit the braid. I then cut the running end of the mono so that I can snake the flyline into it at least 6"
I put a drop of Pliobond at the junction of the 2 splices and at he end of the second splice.
Shooting heads:
I started using them in about 1970. They are an effective tool for searching water. Some people love them - others hate them. I used to use them almost exclusively. I changed to full lines for a while. I then used the full lines with a spare spool with a shooting head. I now use shooting heads most of the time. Under some conditions they are great - under other conditions they are OK - and sometimes they are terrible.
They are much more versatile than the popular Depth Charge type of lines.
Nail knot failures:
I believe when some of the West Coast FFers reported failures with nail knots, they were using 30# tippets for billfish. The fly line coating was pulled off by the nail knot. Certainly not a common set of circumstances.