My work is pretty much all email, text-based handouts and the occasional PowerPoint in my role as a college English teacher. I would love to be able to leave the MacBook home and just take in an iPad and keyboard. I don't have any other computer in my office, but I do have wifi and could buy a printer to hook up to that network.
Does this sound practical?
No only because I don't see how you'd download attachments if you can't receive email via the mail app (ie. Web based mail). Otherwise you may be able to pull it off!
I'm not a fan of the concept of having a regular notebook, mini, or desktop and then having something like an iPad (or netbook for that matter) as a lightweight addition for mobile use. I find there's too much value in having everything I might need available to me in one place. If I'm at a hotel, library, campus, or whatever I like knowing that by deciding on an all in one solution such as a lightweight notebook, whatever I need, it's right there. My files, pictures, bookmarks, pdf's I grabbed from a site 6 months ago, all of it is right there for reference and I'm not left saying "yeah, I'll send that to you when I get home."
I'm sure this doesn't matter to some but then again there are many who feel this same way. I guess it's really all just a matter of what your needs/wants are.
Do you have a desktop or will this be your only computer, period?
I haven't touched my laptop since I got the iPad Saturday morning and It'll probably replace 80-90% of what I use a computer for but there are still occasional things I need OSX for. I doubt I can live with it as my only computer.
I think it's an 100% net book killer though. Unless there are people who use net books as their only PC but that would just be torturing yourself.