I had the TT spoiler and I have to say it worked very well indeed, much better than the Puig taller screen I've also tried. However, I found it difficult to get the clamping tension right and in high cross winds it tended to shuffle itself sideways; in the end it blew off somewhere in Pembrokeshire! I now use one of these...
http://shop.heroblobs.co.uk/collecti...-990-adventure
...half the price, is fully adjustable, bolts on (although it does come with sticky pads too) and works just as well, if not better. There isn't an Aerotrim specifically for the XTZ, so use the KTM version as it is narrower (side to side) than all the others and suits the narrow screen top of the Ten.
Spoilers IMHO appear to be the way to go as the small amount of air that is allowed through behind them seems to stop the dead air/vacuum building up behind the screen. I also put 5mm rubber spacers behind the screen mounting holes to allow a little air up behind the rest of the screen, which seems to have helped too.
However, stopping buffeting/wind blast is all a bit trial and error and depends on a multitude of variables. It's not a bad idea to have a go with bits of card/plastic and gaffer tape to try and see what sort of arrangement of screen extension suits you best. One solution won't suit everyone though as I'm sure you'll find out...