iPod Touch + dumbphone?

Anybody have any experience with this?

Considering that:

a) 90% of my day is spent near wifi access (work, school, home, etc.)

b) most content can be stored for offline use (music, video, maps, articles, books, games)

c) I'm a heavy Google Voice user

Is this a reasonable setup? Am I crazy for thinking I can getaway with a barebones cell plan, or even a prepaid plan, and an iPod Touch? Are there any drawbacks I'm not seeing?

Help me out folks.