I took the plunge and bought a pair of dual control levers, they are the same as the Deore XT ones that are on Graemes' bachetta.
The verdict is still out, but there are a few pro's and cons'
The Good;
I have hamster bars on my bike and tend to hold the top of the brakes while riding. With these lever / brakes, I can hold the top of the brakes and change gears with my little and next to little fingers, so no need to change my hand position.
As the bars are very narrow, I now have a whole hand width of bar to grab hold of should I need to.
Unlike the grip shifts, I am not likely to get so sweaty that I can't change gear
The shifting is very crisp and nice on the rear derailleur.
The brakes work very well.
Despite the rumors a MTB front shifter will work with a roadie derailleur, without indexing issues.
The Bad;
They are probably a bit less aero than the previous set up.
Because the bars are very narrow, routing the cables was tricky and there are now some pretty severe angles involved.
To get the cable angles livable, they need to be set wider apart than I'd like, so the levers hang over the end of the bars a little.
The front shifter is very stiff, but this might be because it is working on a roadie derailleur)
Routing the cables so they didn't interfere with the brakes took a while.
They are a bit agricultural looking, but saying that, they probably look better than the new XTR ones.
The Daft;
The cables out of the box were about 2 inches to short, so I had to go and get a new set meant for a tandem. Its a common issue with a bike thats over 3 miles long.
The cable outer were no where near long enough, so I stuck with the originals.
I need a smaller computer so that it doesn't interfere with the cables.
Net result, I'm not 100% sold, but will stick with them for a while.