If you're going to put a bimini in GSP you have to do a lot more than twenty twists. I usually do at least 50 and I know guys who say they come closer to 100. It makes it a harder knot to finish, but it will hold. I'd also make the loop large enough that you can double it over before doing the surgeon's. That way you end up with two smaller loops. The GSP cuts so easily that one loop will often cut through the loop on the end of your flyline. The double loop seems to minimize that problem. It will still cut, though, so that loop on the end of your flyline should be replaced on a reasonably regular basis.
I've also used Airflo Sightfree G3. In fact, I almost included in my list in the post above. However, I still like the Rio and Seaguar products better. They just seem to be stronger for the diameter though my evidence is only anecdotal. In other words, I haven't done any actual tests to prove it.