I stopped using Ultraseal after a problem in France. It stopped the tyre going down so the nail was in there causing more trouble for days maybe weeks. Finally there was a hole that was too big, fortunately in a carpark in a town on market day 500 yards from a Scooter dealer not at 130 KPH two up on the Autoroute. Patches would not stick to anything Ultraseal had touched.
In rural-ish France they just get on with stuff and we were off about 2 hours later with a new tube. In the UK you'd have lost the day getting home, probably without the bike, had to wait in while they dropped off the bike and collected the hire car and then still had to get the ****** gunk out yourself before any tyre fitter would risk getting his hands dirty to fit a new tyre. You'd be light a days holiday and 200 quid.
Mushroom plugs in tubeless take ten minutes and I can get the rear tube on a Bonneville patched and working in about thirty so long as I fitted the tyres myself using lube and skill not some tyre monkeys ten foot bar. I would actually go back to tubed tyres but they are very difficult to buy. Most bikes with tubes now use tubeless tyres so you need a bead breaker not just levers.
Andy