Hi,
I got my Edge 530 a few days ago - and, indeed, it has the back button problem so I'll need to return it. But in the meantime I've been playing with loading routes and checking out the climb feature. In principle, this feature looks quite cool. But I took a 70 km ride from last Sunday, converted it to a course in GC and loaded it into the 530 then looked at the climb figures. It reported that the total climb was +7000m with slopes up to 25%. Since I live in the Netherlands and the ride I used was basically flat, I would conclude that the calculation is rather off. I repeated the exercise with an MTB route in the Ardennes that I rode that was 1000m climbing over 45km and the 530 reported that it was 2200 metres, with more and steeper climbs than exist on the route.
For comparison I took the same rides on Strava and converted them to Strava courses and then loaded them into the 530. This time the climb feature reported results that are pretty much close to reality. So the 530 seems to have a problem calculating climb information from GC courses.
Otherwise, I'm very please with the Edge 530 so far. The display is a big improvement from the 520, ditto the amount of memory and the maps, etc. Tomorrow I'll take it out on a first serious ride and see how it works out in practice.