Tracy,
1. The disconnected data concept is typically for client server. I would don't go trying to apply the VFP way in a C/S environment. I think it's an error to try to do so.
2. Do you have an example where you really want to update each field while you're filling in a form ? I personally always use the scenario 1. 'Tell the form I want to modify', 2. Change, 3. Submit the changes to the DB.
3. On a PDA in the compact .net framework, connection poolling doesn't exist and there you must keep open a connection otherwise performance is very poor. I don't think that's is really a major problem but I would keep this as an exception, I wouldn't generalise it ...