In reply to euanryan:
If you look at some of the old time pictures you will see we often used just a nut with krab on it, using slings to extend them when there was a danger of them pulling out. Now people use QDs on nearly everything. I use the old method with short slings to extend when needed.
If you ARE new to trad, get the longer QDs with a good bit of play on one end ans the stiff ones are worse at lifting out nuts than none at all. ~You can mix them up with your wall ones if you want, so long as you make sure you do not back clip, a lot more serious on trad as the drag can also lift out runners.