Coralvue puts 2 fans in their E-ballasts.
They also break regularly.
Bang- I'm with you on the power savings.
For me, I run E ballasts. If I had to do it over, I'd probably go back to magnetics. They last practically forever. In most cases, they drive the bulbs better than an E ballast will and will give you a slightly higher PAR value on the same bulb than a E ballast will.
I run coralvue and Icecap ballasts. They're ok. They're cool running. Never saw a difference in the electric bill though.
You can also DIY M kits very very cheap if you feel like doing a bit of wiring, you can set up a 250/400Watt setup ridiculously cheap with magnetics pieced together.