They work fine in the CRJ, even at high indicated AS where it gets noisy. The 12 Db ANR is a good reduction in noise, but does not provide anechoic silence...for a truly silent ride you need a full earmuff style ANR like the Bose.
I like the 850 cuz it's cheaper, lighter, requires no batteries, and cuts enough noise to eliminate any risk of hearing damage, and reduces fatigue.
If you use a battery powered unit, you lose comms when the battery fails.
I picked the 850 after trying all the available options in flight...most guys will let you try their headset for a while.