>One of my clients (also a programmer) has recently decided switch his main development tool from VFP to Delphi.
-- snip --
>I would really like to hear somebody else's take on this, to help me through a strategy here.

Erik, perhaps a compromise in a different direction? Suggest that he send you to a Delphi class. He pays the tuition, you don't charge for the hours spent in class. This way you'll get a (relatively) quick view of exactly where the differences are and what you'll need to work on to be productive.

With a little preliminary work for a few evenings you should be able to take an intermediate-level 5-day class, and end up ready to write apps at the end at your regular rate of pay, with both of you feeling that your productivity is not seriously impaired.

I've found that going to a class with an existing application in mind leads to much faster assimilation of new techniques.

Just my $.02
Barbara