If the seam tape is coming loose, I'm not sure if the jacket can be saved. (It may be possible to re-attach the tape; I just don't know.) If it can't, you'll get your wish to try one of the new jackets.

Beyond that, it seems to be a question of cost/benefit: will the time and money you save extend the life of the jacket enough to be worth it? There comes a point where, no matter how great it has been, it deserves to be retired. (Just today, I retired the 3 or 4 year-old OR Helium jacket I'd been using to become my everyday town rainjacket, and the 10 or 12 year-old Patagonia I-forget-name-but-it's-H2No-fabric that had been my everyday town jacket will now become my golf jacket.)

Regarding its replacement: I happily used my Patagonia jacket for backpacking for 5 or 6 years until I was lured by a 6 ounce weight savings into springing for the OR Helium (Pertex) when it came out. It worked just fine in light, intermittent rain. However, in prolonged rain or heavy rain, I always ended up wetter than I did in the Patagonia. I could never find a leak, but I wasn't moving around enough to attribute it all to perspiration. When I replaced it today, I chose the Patagonia Torrentshell (the successor to whatever the name of mine was), even though it put 4 ounces back into my pack. Function always trumps weight - a 6-ounce rain jacket that doesn't really keep you dry is a much worse choice than a 10-ounce jacket that does, even for an ultralight hiker!