"Electronic ballasts don't have a short life expectancy but muffin fans do."
I sold electronic components for 22yrs and I'll bet a capacitor/diode/chip/etc will fail before the muffin fan will. Today's component technology is far ahead of what was available just 10yrs ago. Surface mount technology, pick & place machines have almost eliminated the need for the human hand when it comes to assembly, which was the cause of 70% of the failures, IMHO.
I'm using Digital Greenhouse(probably private labeled) from HTG Supply and it has preformed well.
That's surprising since I have had fans die on all sorts of things from computer power supply, Tivo, video card coolers, etc. I have had electronic ballasts running on my reef tank for 6 years without any problems and hear about similar longevity from other hobbyists. BTW, these are PFO brand ballasts.
Yes the fans can be replaced but the warranty on the Lumatek is very good and using that link I supplied above, I paid about $10 less for that ballast than HTG charges for their 600w.
And if you need more light, the dual 600w is even cheaper than 2 individual ballasts.