The GUI interface stuff and the display of PEMS in C# is pretty good "as is". So we give up the Report Writer, which frankly I would miss. We give up VFP databases. As much as I like VFP tables, it would be better to have a single file database. VS2005 Professional comes with Crystal Reports .NET. Even though there are a few features missing from the stand-alone version of Crystal, CR.NET is still (IMO) a better report writer than VFP's.
It takes a lot more time to work with SQL than it does with Fox tables. Out of curiosity, how much work have you done with SQL Server?
Kevin