I use Muskol (30% DEET) and find it pretty effective.
The old thread you found from 2005 was referring to 95% DEET Muskol, which has now been banned in Canada (anything over 30%, IIRC). The 30% won't really melt plastic or anything, although it might mar the finish if you spray it directly onto the plastic. I'm extremely careful not to pray it onto polycarbonate lenses.
For heavy duty, nasty bug-country stuff, I still have half a bottle of the old 95% DEET Muskol and you can still get 95% DEET products from the US. But generally the 30% stuff is effective enough.
Dragonflies rock. I was camping near a pond once and had a swarm of them come out in the evening when a cloud of mosquitoes came for me (I could see them backlit by the sunset). Big ass dragonflies the size of a pen. Watching them zip around guylines and hunt was amazing: they're like miniature flying sharks. Not a single one of those mosquitoes got near me, either.