I have the 50 watt Marineland stealth in a 2.5 and haven't had any problems with it. It keeps the temperature at 78*. I also have the 10 watt pre set marineland heater, it works great for 1- 1.5 gallon tanks but wasn't keeping a good temperature on the 2.5 gallon.
I think part of the problem with the marineland heaters is that the company says you can do water changes with the heater still plugged in. I would never risk it, I always unplug the heater and filter while doing water changes and turn them back on when the tank has water in it. The heaters are suppose to be designed to shut off themselves if the water level drops too much. So some people think it's safe to leave them plugged in while doing water changes. I would never risk it with any heater.
If you are curious about the Marineland Stealth heater problems you can click here http://www.plantedtank.net/forums/eq...ro-heater.html
If I were buying a heater again, I wouldn't go back to Marineland's products. I think they mishandled the situation and made it difficult for their customers. I don't like to support companies with poor customer service.