I have been using Spectra lines on most of my .35 to .40 size models for a couple of seasons now, and exclusively on the smaller 1/2A stunt models and trainers. I find them to me much more durable and love the feature that they do not pig tail and kink. For flying stunt, I have found they shine the best when doing the vertical and overhead maneuvers. I have found that every model I have used them on has had better performance in these maneuvers. For a typical ARF Nobler, the weight difference between metal and Spectra lines was very significant. I forget the exact numbers but when I made up a set for a Nobler ARF, the steel lines and reel weight something like 2 1/2 ounces while the equivalent length of Spectra lines and reel was a few grams, more or less the weight of the reel and metal clip..
I wonder why some use line that is so heavy for flying smallish stunt models. I weigh the model and determine what the pull test would be, then I add 10 pounds to that and that is the weight of the line I use, usually rounded up because there isn't a very wide selection of line at Bass Pro when I go there. And I have been using Spectra brand, just to avoid any confusion on my part, and buy it locally, as I have both Bass Pro and Cabela's store right close to me. I use the loop and knot that is in the video presented in this thread by Mike Stinson, with the loop doubled like he shows because it just makes sense, and add in the welded metal rings suggested by Dennis Adamisin, then I can use and change normal line clips as desired. So far I have not had any issues with the lines I have made up and use. I remember reading that some one from over seas suggested just a drop of clear silicone to help secure the knot against slipping, as it will remain flexible, and that may help settle anyone's fears of a knot slipping.
I have mentioned before that this thread contains just about ANYTHING a person could want to know about making up a set of lines using Spectra, and it should be pinned to the top of some section, probably the "At The Handle" section, just to make it easy for people to find.
Type at you later,
Dan McEntee