I recently upgraded from an eTrex Legend HCx to the Oregon 400t.
One option I miss already is to save tracks to data card. This option basically took each track and saved it to a daily log (20091204.gpx) for example. Just track data, but it was really nice since I could clear the current log and know all my tracks were saved if I wanted to go back and look at them. I would manually archive them on a monthly basis.
I realize the current method is similar, but having it broken up by day made it very easy to go back and find tracks I later needed to reference.