9,4 ×10^6 out of 17,0 ×10^6 people use WA in the Netherlands, according to http://www.marketingfacts.nl/b... I use both WA and WA GB (for testing on my dual sim ;-)

Try MS Groove. It supports offline working, synchronizes your data (and forms and stuff) when your connection is up, and stores local copies in an encryped 'vault'. ...But there's a catch: you need to build something for your geared Gmail and Groove to sync.

Indeed, use it. Take a set of powerusers and a couple of dummies. Give them various assignments. 1) Track and trace their eye-movements (use GUI-students at universities) 2) Track and trace cursor-movements (google for ajax tools for visualizing in-browser-measurments) 3) Track and trace number of clicks 4) Track and trace users' routes to solutions 5) Track and trace time to complete their tasks 6) Take time to ask and hear what they have to say about it