Aqueon pro heater

I was just wondering if anyone had any experience with these or have heard of any issues. I picked one up today to replace an old Aqueon glass heater that started to have condensation in it. It had lasted me a little over a year. I was thinking about getting the Marineland Stealth Pro and did some research -- found out they are little grenades. I guess after reading about that ordeal I've been very paranoid about submersible heaters in general.

Product in question: http://www.aqueonproducts.com/products/pro-heaters.htm