John, in some instances, I've converted VFP modules to .NET in less time, in the same time, and in more time than the original ones were quoted as taking. It all depends on what the objectives were. Getting it down to the hour or even the day is implying a level of accuracy that doesn't exist.
But I've seen .NET talent out there that can surely build components in at least the same amount of time as a top-notched VFP developer.