When I swapped the flat bars for drops I put the SRAM twistgrip onto a 'T' bar bolted to the stem riser. It has worked OK but a simple adjustment has made gear shifting easier.
The 'T' bar has a slight angle to it, similar to handlebar stems, so you can flip it over to gain a little height or dip it lower. When I used the bar to cary my 'bar bag I had the bracket tilted up and left it that way when I slid the twistgrip onto it. This brought the twistgrip very close to the underside of the handlebar and was a little cramped. I have just flipped the 'T' bar over and slid it a little further down the stem riser and this has made the whole system easier to use.
I have also fitted a bell to the other side of the 'T' bar. This bell is designed to slip into the end of handlebars and produces a nice old fashioned (and friendly) "Ting-a-ling" instead of a "Ping"! From the front the 'T' bar looks a bit lopsided. This is an optical illusion as the twistgrip covers most of the right hand side. It does mean that if I wish to add another chainwheel - using Xootr's kit - the other twistgrip will slide onto the left hand side and even things up! Using the 'T' bar frees up the handlebars and prevents clutter.
Some time ago Xootr changed the stem riser of the Swift by increasing the external diameter. The top two or three inches are still 1.1/8" in diameter, to take standard stems, but below that the tube is much fatter. This will restrict how far you can move the 'T' bar and I am not sure why Xootr changed the specification.
It just shows how a small change to the set up can make life a little easier. The 'T bar is sold by the UK cycle shop St. John Street Cycles - sjscycles.co.uk.