I have tried this app for a couple of days, and I must say it works great!.
I like to stay online on MSN during the days, and with 3g that consume ALOT of power, but with 2g it dont consume as near much power.
I also have Exchange sync (always online) and that works just fine with only GSM.

However: I have a suggestion.
Is it possible to automagically trigger the app to use "dual" or 3G when a browser window is open?
It would be nice to not have to open the app and switch to 3G manually.