Originally Posted by znomit

No real reason to upgrade from the 30 series unless you want better button control on the 840.

PS, I never knew there was a wired power mount for the garmins. I wasted a few minutes looking until I saw the price, 180 US$ with cable. They really don't wan't people buying this or the similarly exorbitant power pack.
https://www.garmin.com/en-US/p/784702/pn/BUNDLE-EPM-UAC