Not used the FixIts yet but the company are amazing to deal with. Highly recommended
I've been using these sticks many times without any problems but i've found that you do have to leave them in very hot water for at least 2 minutes before shaping them. Customer service is 1st. class as well.
Lovely and clean and easy to use. Great to know it can be re-used over and over. No nasty smell like some mouldable stuff