If you are going to get a PDA, to get the most out of it you will need a weather meter
of some sort to get temp, pressure, humidity and wind strength. Kestrel
seems to be a brand a lot of people use, although there are a number of others You will also need some form of angle meter.
I just have a rangefinder, Leica 900, and a wind meter
. I have two sets of drop charts one for 2500' and the other for 5000'. These charts also have drops for different angles.
I am limiting my shots to 600 -700 yards and my drop charts work fine out to that range. With your edge I would imagine that you will be shooting further so the weather meter will be a lot more important.
Rangefinder Swarovski, Zeiss, Leica (probably in that order)
Angle meter (I just use a protractor with a piece of wire that hangs down)
PDA running Exbal or something similar
Weather station as mentioned above
Lots of spare batteries!!