Persuasion is a different vice then informing. These heaters were marketed as shatter proof, and with the ability to shut themselves off when removed from water. This alone negates all the ideas about plastic expanding and contracting.
On a side note, Don't you find it a little alarming that even though Marineland States their is no recall. You can't find the Stealth Pros on their website anymore? Only the Visitherms?
Marinelands Specs "The Marineland Stealth Pro heaters are constructed using a shatterproof injection-molded thermal plastic casing to protect them from wear and damage. They feature bi-color LEDs with an Optic System that illuminates the translucent temperature dial red when heating, and green when the temperature has reached the desired level. A mesh heating element with mica cora, coupled with epoxy fill ensures the most efficient heat transfer and durability. A safety shut-off mechanism powers down the heaters if removed from the water, and automatically restores power when returned to the water. Stealth Pro heaters have certified accuracy to +/- 1 degree Fahrenheit. 200 Watt model is ideal for aquariums up to 55 gallons."
Again, not trying to persuade I just would rather no one follow your It hasn't happened to me example and wind up with a house full of water and a room full of dead fish because they read on MFK that some guy didn't return their so why should I?
Mike