Check out this review of 3 single handers in Y&Y UK, thing to look for is not the cat but the RS700, read the 'off the wind' system. You'll see it has a 'pump' system to raise the spin one handed. Anyone at a UK club seen this up close? A friend of mine had a 700 when I last lived in UK, but I never bothered to check this system out.

http://www.shadowsailing.org.uk/documents/TrapezeSinglehanderGroupTest.pdf

See page 24 and 25 of the owners manual to get some pictures of how the system works:

http://www.rssailing.com.au/pdf/rs700ownersmanual.pdf

My concern would be how quick you could get the spin down with the halyard under enough bungy tension to make the system work. It's tempting to try it out, in my case I think I can get a lot better at the two line system before I start changing things too much.

I prefer two line oover one line as the split drop gives you steering window without the risk of running over the kite and you can set up for the hoist before you round the mark.