Ok Gaz before everyone climbs into you, lets simplify some of your points;
1. Trad in the berg: Your choice single or double rope (the US climbers trad on singles all the time). Most SA climbers prefer to trad on double ropes because of the tangible advantages. In the US they are normally following a nice clean crack line so the gear goes easily on 1 rope. Not so mostly in SA. Ok maybe google the list of advantages of using a 2 rope system or read a good book.
2. One of the main reasons to use a 2 rope system is so that you can abseil further i.e. Tie 2 ropes together, pass through anchor, abseil on double ropes & pull the system. This implies that you know how to set up a rope so it can be pulled or you will be ascending again to release the ropes.
3. If you are climbing in the berg then forget the beginners back up rope thing & use a prussik. Once the first person has abseiled like this they can do a fireman's belay for the rest of the group. I know "big kids" stuff but hey you are already messing around in the berg. Now you are back to two ropes but can abseil a full rope length.
4. Normal disclaimer for you Gaz - get someone to show you all of this & learn it well. Here's my suggestion that you go see Gavin Raubenheimer again.
The double ropes thing is generally better, but I understand you want to cut down on weight. Most climbs in the berg were opened with ropes barely 30m long, so maybe you should make up some special shortened half ropes as that would be optimal. I think some Beal ropes can be bought by the metre. Alternatively use a single bi-colour half rope which gives you the best of all worlds in your case.
http://www.sterlingrope.com/product/155 ... olor_9.2mm
Okay I could not find a Beal at this point but I am fairly sure you will be able to get one.
Or climb single rope & use a joker...
All the best & figure out a system that enables you to climb safely.
