Link doesn't work Catfan !
Also you want to engage the T-foils on the upwind as well. Here they stabilize the rig, something most designers try to achieve by using lightweight carbon masts and lightweight sail cloths like cuben fibre. Interestingly, the better solution is to have two 100 dollar T-foils on your rudders. The effect is much greater and the expense much lower.
The only drawback I can establish with respect of the T-foil rudders as they are available now is traversing the surf. Ones that issue is solved then we'll all be sailing with them.
Wouter