I've had a Trail Charger going on 8 months now. On average I'd estimate I fill a dozen guns a week. Only maintenance I've done is twist the cap on the grease pot. It arrived with antifreeze in the water pot, and that hasn't needed any changing.
It does fill slowly, but I like that. Makes me feel like it will last a long time as it doesn't do a bunch of crazy stuff when you turn it on like a Yong Heng (I had one that blew up almost immediately). It also doesn't give off noticeable heat to speak of, even after running for a while and putting your hand next to the fan.
Big fan of the Trail Charger and no regrets splurging for it. I love how much water it spits out the bottom tube when you open up the pressure valve. I'm sure in many compressors all that water goes straight into your gun unless you're running a burly filtration setup. I only use a small filter on my fill hose and it seems like it's not even necessary.