We very rarely wear headsets in the Challenger but we have the 750's. I wore the 5x5 for a couple of legs and didn't like it at all. They just seemed unnatural and uncomfortable to me.
If you're not concerned about having ANY decibel reduction I've got the perfect headset for ya' - I just can't remember what it's called!! ha It fits in your ear and they send you a wax kit and you take a mold of your ear so it's custom molded to your ear. Pretty slick set up. Not that expensive - I seem to remember them running about a buck fifty or so. Bad things are: the turn around time isn't that bad but definatley longer than picking up the phone and ordering a headset from Sporty's and since it's custom molded to your ear I believe that it's side specific(ie - you might have to have one for the left seat and the right seat if you switch seats - not 100% sure).
Check out marvgolden.com - Telex has some variations of the 750 - including a one sided and ANR model you may be interested in.
I use the Telex Airman ANR 500, I wouldnt trade it for the world. The 9 votl battery last 50hrs. of operation. Hearing conservation is important and any help I can get I appreciate, it also keeps ATC communications extremely clear. I don't know about other airplanes but the cessnas I've flown have alot of wind noise at speed, on a long trip this can be very fatiqueing. I would highly recommend spending the money for an ANR light weight headset. If you check Ebay, motors under parts and accessories-aviation and limit your search to Telex you will find a ANR 500 with a bid price of 202, bid closes today though. The ear piece mentioned is from EARMOLD Design, Inc out of Minneapolis, MN. My boss wears this product in the 650 and he constanly is asking "what did they say"
A good pair of sunglasses and a good headset goes a long way in makeing your every flight more comfortable which makes it more safe.
I use the DC ANRs in my airplane and when we tried them in the CE-500, it just didn't do it so well, we figured it was somthing with it not reversing the phase, (how it accomplishes the ANR)
But if you are saying the telex 500 makes the grade I am on my way, they also have an 850anr but that Headset receives power from microphone bias (Active Intercom, Hot Mic) and we don't, (obviously) have a hot mike. or an intercom for that matter, I am going to call telex and see what they ave to say about it.