I have a sterling 8.8 setup, they stay as dry as any other "dry" ropes I've had... I also have a sterling 10.0 single and it is a fine rope as well.
Mmmmm - There's nothing like a face full of DWR spray the first couple times you rap on a new dry rope that has seen some water. (Tastes terrible too!)
To me, a 70m rope means another 30 feet of rap tangles, extra weight and placing extra gear OR longer runouts. Not to mention the communication factor... but then again I am not particularily "light" or "fast" or "extreme" for that matter so what do I know... :-)
Plus, the factory is in the next town over from me here in maine - buying local products - excellent!