Tom Nakashima writes:

The knots I know how to tie, and I never use the loops, I cut them off.
I was wondering if there's a difference in the way the fly is presented with
loop leaders

Some folks insist that a loop connection can produce a hinge effect when
casting. I have used the mesh "Chinese finger trap" connectors Orvis likes so
much, and loops made from mono that has been nail knotted to the fly line. I
have never experienced this "hinge effect", however, I can understand how it
got started. If the finger trap mesh thingy is installed improperly, it could
hinge when the line is not forced all the way to the loops end before securing
it.

There are other options for connecting fly line to leader. Eagle make leader
connectors which are small plastic thingies where the fly line is passed
through and a simply knot made to hold it from slipping out. The leader is
also passed through the opposite end of the leader link and a simply knot holds
it in place. Lots of folks on roff use this method.

Still another method is a recent proprietary release from Sci Anglers. You buy
a kit with a plastic tool that installs a plastic thingy to the end of your fly
line. The kit also allows you to attach a special proprietary leader sold only
by Sci Anglers that attaches to the thingy. When you are through with that
leader, you insert another thingy (there are five in the kit) and attach
another leader. OR, you could tie a small perfection loop in the butt end of
the orginal leader and go back to loop to loop.

I've tried all the above methods but prefer the nail knot with a perfection
loop at the other end of the short piece of mono.

ymmv, of course.

Dave