I have to say I was also tempted seriously in configuring my GTI with the Pano Roof, it looks good when closed. But after seeing the video I am glad I didn't. The Wind Deflector is fugly!
I am also concerned if I do drive at high speeds with the roof open it may cause minimal drag or problems with the roof vibrating etc, as others have mentioned.
In my opinion, best use the Air Conditioner more, it may be cheaper.