I've got an Explorer and a Safari, and have used both at 6"2 350. The limits seem to be fairly conservative.
265 here and use the hh ultralite occasionally with no problem. Most products will test the rating at that weight several times and hh stuff is pretty good quality and seem to stick behind their product so I assume they tested that thing many hours holding 300 lbs so I wouldn't worry about it.
I have an ENO Double and it's rated to 400 lbs whereas their straps are only rated to 200 lbs a piece. So I am currently looking for a replacement set of straps and will use these with a 1/8" amsteel blue whoopie sling for suspension.