I know you said non-glass, but Eheim Jager heaters are about as reliable as they get in my opinion. Of course, any heater is best used with a dedicated controller for maximum safety. I have not had much experience with non-glass heaters, although I have had experience with the new Aqueon Pro heaters. They are plastic, and remind me of the old stealths minus the exploding! They seem really reliable as well, but I can't give any long term results since they are relatively new.