I'm tempted by the idea of just taping the hairline for events etc, but it's hard to apply tape while the system is still on, so I would have to only do it when I fully remove. I'm not against the idea if anyone has any experience with tape, UTS and an active lifestyle!
I'll check out Davlyn Waterproof Adhesive. I remember when I first went to a salon I had huge issues with the system staying on. I had to go back in for an emergency attachment because the glue I was using (the same that I use now strangely enough) just wasn't holding. They stuck it on with this heavy duty Davlyn brand glue - I can't remember what kind it was though. It smelt like the inside of a mechanic workshop, so I wouldn't want to use it all the time, but it was a strong hold!!