I love the Won Brothers Titanium heaters too, they heat well and I have a 1000 watt unit that I use to quickly heat up water for tank changes.
The only thing I don't like about them is that I have also found that they are off a couple degrees and more importantly, you can't see when they are kicking on or off by just looking at the tank.
Up until recently, I have always swore by the Rena Excel heaters that go up to 300 watt. They have been reliable and you can see the red light go on and off from a distance. I like that because there have been times where a heater was not set right or was going wacky and I knew that the heater shouldn't be kicking on and it prompts you to check it. With the Won brothers heaters you can't see it at a distance.
I like the Rena Excel and Won brother heaters the best for different purposes. For the tank disply, I think I would rather have 2 300 watt units of Rena Excell in my 100 gallon tank than just a 500 watt unit of a Titantium heater for two reasons. 1 is that I can see the red lights go on and off and also, if one heater fails, you have backup the other heater will kick in. Really important in the dead of winter.