When my windscreen got replaced (about a month ago?) the "gel pack" was a roll of clear gel tape that the Autoglass tech cut to fit.
In all honesty I think any gel type stuff would be fine as long as the thickness is correct. The pattern part may have been ok had he not stuck his finger in the middle of it 
causing it to become dirty and less tacky. The sensor tack is good as its applied via a syringe and finds its own level
Only problem being that if you ever need another screen your sensor will most likely need replacing because they'll need to cut it off the screen.
Autoglass put a new screen in my R at a month old, fitted a non VW screen which was perfect even though i asked and was denied OEM, they fitted a new OEM gel pack, all in all i was very pleased with the job, i did take the car to their premises though and was aloud in the workshop to watch.
