I have a bose X for GA and I have a lightspeed mach 1 for the "other" job in the quiet airplane.

Bose X my airplane is pretty loud so I went with the best.

before the Bose X I used the Bose QC2+uflymike which worked great but, the actual headset was starting to wear out and rattle after a year of line flying.

I've owned a DC 13.4 for 9 years, it flew with me for my first 4000hrs. 2 sets of replacement ear gels, one head-pad(wasn't necessary, but did it anyways).

I also have had a Clarity Aloft Pro for about 9 months. It's my X-C headset, works very well, Db's are greatly reduced. Does pinch a little bit if you put it on too tight, but constant wrenching on the wire frame has finally made it fit comfortable for over 3hr flights w/o any issues. I just wore it for 9+ hours yesterday flying a Meridian from Indiana to Portland, OR.

Sound-wise, I can't tell a difference between the Bose X and the Zulu's but it's easier to plumb music into the Lightspeeds, so that's what I went with. The bluetooth thing is cool I guess, but you can't use it once you're higher than about 040.

If you can't afford them, any ANR headset is better than not having one. The "I'll wait until I have a real job" argument just doesn't hold water because the noisiest planes you'll ever fly are the ones you fly when you're getting started!

As far as hearing mechanical problems, I think you can hear them easier when the drone of the engine noise has been suppressed. If you can't afford an ANR headset, just don't buy a digital flight computer, expensive flight bag or a bunch of other useless electronic crap and you'll have the money.