Octopuses don't sting, they bite, they don't climb out all that often, and they don't ALWAYS inject venom into whatever they're biting.
All that said, if you like blue rings, maybe get either a dwarf octopus, or a larger species. Not only are they not venemous (well,as venemous as BR) they are probably MUCH more enjoyable. Some of the comments posted here are way out of line. Some people have extremely severe reactions to ANY octopus bite. it depends on wether or not you're allergic to the venom. For example, today, I got squirted right in the eye with about 4 polyps of zoanthids that I was fragging, and accidentally pinched them in a crack in the rock they were on. Nothing happened. No numbness, swelling, temporary blindness, etc.
I've always wanted a blue ring myself, but not until we have completely automated fish tanks that I don't have to stick my hands in ever.