I've looked too and came to the same conclusion as you, there really isn't another option and even though mine never has problems there are clearly people whose Hydors have been unreliable. There is a tutorial you can search for where someone made a DIY inline heater with a regular heater stuck into some PVC but it was big and ugly, I'd rather just stick with the Hydor one and hope it keeps being reliable.
Apparently Fluval was rumored to come out with a special inline heater that connected directly to the G3/G6 filter and used its temp sensor but I don't think it was ever released.
Apparently Fluval was rumored to come out with a special inline heater that connected directly to the G3/G6 filter and used its temp sensor but I don't think it was ever released.