Forgot to add -
We've been trying out an Edge 530. It has been a bit of a struggle as it seems to like to instruct us to "Make a U-turn" often even when we are on a straight road going in the right direction or keeps sending us back to the start even though we are right next to the proper road/route (we were using RWGPS downloaded .fit file). At the same time of trying to figure out what is going on with the turn-by-turn, we had to keep looking at the screen which was hard to see in the autobrightness mode during the day, as we both have presbyopia (need +2.00), although I can normally read fine in bright light) Combination of incorrect instructions by the navigation tool and lack of visibility was very frustrating. Increased the brightness to either 70 or 80%, can't recall, which helped a small bit but did not solve the problem. But with that the battery started draining really fast.

Jury is still out on whether we will keep this 530. The lack of clarity in the screen, at least for us, and the weird navigation responses made us both want to throw it int he middle of the street.
I should probably post some a new thread on if anyone else is having trouble with the screen brightness on the 530.