What I've found is that if you want a temporary fix, the Loon product works well. Sometimes it can be a permanent fix depending on where you're leaking.
+1 on Aquaseal. The trick with this stuff is to apply THIN layers. Less is more with this stuff. Add a second or 3rd coat if needed, but again, THIN layers. I learned the hard way with this stuff on old waders that are no longer in use. Too much Aquaseal can be problematic depending on where you're applying it.
Can you live without them for a while? If so, I'd recommend contacting Simms and have them do the repair. They'll do an excellent job and likely find some areas in need of attention that you may have otherwise missed. I sent mine in a year ago because I knew I had an issue (tear in the leg--thanks barbed wire). Upon getting them back, I was amazed by the number of repairs they made.