Hi L.
i started with a DC (No ANR) for my private training, didn't really like it, just too loud and i hated these stupid plastic earpieces (and the colour). So i bought the Lightspeed XLC20, i used it in all kinds of Helicopters for almost 1000 hours.
The noise reduction worked fine at the beginning, but unfortunately it broke down at one point.
After a while i started flying around with ANR just on one side, then the ANR broke completely down, at the end i couldn't hear at all on the left side.
Like i said, i liked it alot at the beginning, maybe i just had a bad pair, but i wouldn't buy a Lightspeed after that experience anymore.
I replaced it with a Bose X, and that is by far the best Headset that u can buy. It's extrtemly comfortable on the Head, and the ANR is excellent.
I know it's way too expensive, but if you wanna do yourself a favour, go for it! You won't regret it!