GPS:Just out of interest: I have the eTrex Legend HCx
https://buy.garmin.com/shop/shop.do?pID=8701Apparently it does have a colour screen.
I haven't used it for so long that I have forgotten. (Says a lot doesn't it)
A GPS is a "nice-to-have"
MAPS:Overall I still find navigating with a map much more practical and pleasurable.
It gives an great impression of a much larger area, indicating caves, passes, paths etc at a single glance.
With a GPS I find you lose your scene and spirit of place. The Genius Loci, if you want to be academic.
The Drakensberg in particular have probably the best maps in the country, for all parts of the 'Berg.
Take the GPS only if you need a helicopter to come rescue you.
Oh, and for that you will need to know what reference system and coordinate system the particular rescue aircraft prefers.
Think about the practical navigation:
To my knowledge there are no 'navigable' footpath software available (Think: GPS metallic voice saying: "Turn.....left.....at.....waterfall....Follow.....steep.....path......to......next.....cairn")