I tried the Telex 850 and QC2 with uflymike mike setup.
I had the Bose X but finally tried the Lightspeed Mach 1 and loved it. I paid the extra $125 for custom ear molds.

I would never use another headset in the CRJ. I wear sunglasses and find the bose qc2 and X push on the sunglasses frame and after 6-8 hours hurt. Same with 850 but not as bad. The Mach 1 has really great mic pickup. No hissing.

Here is the order I would place on the above headsets.

#1 Lightspeed Mach 1
#2 Bose X
#3 QC2
#4 850

(#3 and #4 are very close tie. QC2 is full ear cup 850 is on ear. both good, just not as good as above.)