Tyre Weld, suprised at the results....

Has anyone used the various brands of tyre weld? Got caught out on a machine at work during the week, normally I'd just plug the hole, but without a compressor in the field that wasn't an option. Dubiously I gave the tyre weld a go. Amazed that the little can put 20psi in a completely flat tyre, it fizzed out the hole, sealed and got me back to the yard no worries. Still have my reservations though, the instructions say it shouldn't be kept over 50 degrees so it's not really a substitute for keeping a spare in the boot... Impressed all the same......