I have the applicator gun but just squirted a small amount on scrap cardboard, mixed it, and applied it with a paintbrush. The gun really pushes alot out and fast, and I think it would be impossible to do any precision work with it. Maybe if you were bonding huge sheets together or something. If you were just doing something small, I'd pass on the gun and just push the stuff out with your thumbs and make sure each cartridge is relatively equal. Of course, if you are building another one of those shelters...it could get time consuming.
It states working time to be 10 minutes but you can pull apart the pieces for probably 30 minutes which makes it easy to adjust seams and stuff. It starts to become difficult to apply with a paintbrush (becomes gummy) after the 10 minute mark. I mix small batches at a time cuz this stuff gets pretty pricey. I have limited experience, but it probably takes full 24 hours to dry and then another 24 to dry clear (the stuff on my bag is still a bit milky after a day or so).
I actually used the 3M tape on a couple of other test samples and found the peel and shear strength to be less then the Hysol but still acceptable. Also, the tape is so tough to line up and apply all at once, especially on very long sections (ie. like a bivy). This cuben is really thin so sometimes if you breath or move you arm fast it will move the fabric and mess things up. The Hysol allows for re-application and adjustment.