In reply to Richard: Good point about making the rope ends easy to find, I hadn't thought of that. I guess it makes packing up easy as well: tie each end of the rope in to a tape loop, pile the rope on the tarp, fold it up in a parcel and stuff it in the rope bag. Job done.
I'm not so sure about the lowering-off risk, as I would normally expect the person lowering me to be tied on to the other end of the rope anyway. However, I am not going to belittle it because it was been brought home to me forcefully the other day when a friend of mine came back unexpectedly soon from a trip to Spain having fallen about 4m to the bottom of a crag that turned out to be 2m higher than half the rope length. She landed on her head but her helmet did its job and she survived with severe concussion and a gashed elbow (but a totalled helmet). She's not allowed to climb until the dizzy spells have stopped. Remember, kids: wear a helmet and make sure the end of the rope is secured *somehow*.