For better or worse, it appears that I have to start considering replacements for my 20+ year application of the venerable Teeny 130 fly line. I've spent hours reading sinking line information on SA, Rio, and Airflo websites. I believe there is merit with the current technology and materials. The T-130 is of old design (low tech) and I've just gotten robotic on how I use it, etc. IMO, it's a Type 3/4 and use it as such....... I would appreciate personal opinions on (1) SA Sonar, (2) Rio Deep series lines and RIO 24' sink tip, (3) Airflo sinking lines. To pare down the replies, I am only interested in 3-4 weight rod applications. I've used the T-130 on #3 or #4 rod (RPL/LL/XP) all these years. (I use a 490 RPL or XP like a 5 wieght) I also like thin diameter lines as is the T-130. I think that is why I stuck with that line for so long...... The SA Sonar intrigues me with its claims of different sink rates integrated into a single line. I have no preference either way with hang markers..... Thanks!