Twisty design will allow increased contamination of the o-rings and threads by grit of any composition that exists in the environment it's used in. The same would also be true of chemical agents, both liquid and gaseous. A twisty switch sealed with an o-ring is MUCH MORE vulnerable to degradation from any contaminant than a stationary o-ring seal made with the same materials. There are industrial environments that would seem to pose real maintenance problems for twisties.
Living in hurricane country, I keep a half-dozen Tektite dive lights ready all the time, but other than that I'm kind of tired of big twisties that take two hands to operate.
I still buy little one hand twisties, though.