RE:Overlining .vs. Underling
I think clear line technology is evolving. The 444 clear holds a nail knot and I've never had to stretch it (although I can't say it didn't need it once or twice for the first few casts!).
The Monic lines are now freezer-proof, as Bob Goodale told me "put it in the freezer" and so I did. It was still supple when I took it out. The line sample we will be testing in SWFF size is not clear, but I have complete confidence that it will take coldwater use without coiling. We'll give it heck.
I also like the Rio striper lines, although they are not clear they are very stealthy and cast long lengths well.
Many folks cast the 325 grain on a 9wt, which is WAY overlined for the recommended grain weight. Casts well though, provided the running line out of the guides is kept to a minimum while false casting.
Bill got me hooked on the full sink uniform sink lines. They are great for long false casters (like me). Although they are not as easy to throw moderate distances as the QD series 444 lines (T-300, etc) they do allow for aerializing long casts.
I think the best recipe is whatever makes the rod's flex/reflex power work for you according to your casting style and fly size.