>The main problem we will face is the fact that the Programmers will have to learn 3-tier design as well, and I think this will at LEAST double the work.

That may be true, but that's a skill that will serve you well whereever your programming skills take you.

I learned n-Tier with Fox a long while back. Now I can't imagine building anything non-trivial any other way. It's just so much cleaner to put an app together like this and it makes maintenance a lot easier.

And the skill is portable. Once you know it it's easy to port to another environment. For example, in a .Net app I built recently I was able to build an n-Tier framework without adding significant overhead to the project because it was easy to identify the needs and simply get down and code them.