I would go for something like this if it turns out to be secure against viruses. Just to do online shopping, banking, PayPal etc.
Over the past couple of weeks I had one hell of a job getting rid of viruses from computers of friends and family, including my own when I clicked the wrong link. And I'm supposed to know all about this stuff!
[Yes, I do know about NoScript, Avast, AVG Spybot etc]
Interesting analysis but I personally struggle with the concept. Until net access is truly ubiquitous, (and a lot cheaper than it is currently when roaming internationally), I would personally not go for anything like this. Think about all the holes in AT&Ts coverage alone.