At the moment I've new tubes with no puncture sealant, though I've used it in the past. The tyre fitters suggested this stuff has no value when you have a puncture and unbalances the wheel.

I had a rear wheel puncture last year (masonry nail) and the tyre went down like an Italian centre forward even though sealant was installed (notably at 70mph on the motorway)

So, my question is..has anyone used it and found it worked when they had a puncture? Is it worth the bother?