I think the problem is on what Database will be used as Back-End on your Client/Server app and not on the whether VFP is a true Client/Server app.

I would say VFP is very very capable and in fact offers a new paradign shift of a
Client/Server apps (Old Style: VB, PB, Delphi, etc. which do not have Native Databases) because VFP offers the following options in designing C/S apps:
1. Use VFP as your Front End and at the same time its Database/Tables as your Back-End
2. Use VFP as your Front End and make use of other Database (Informix, SQL Server etc.) as Back End.
3. Use VFP as your Front End and divide the data workload into two: VFP database and Other Databases
4. Use Other tool as Front End and use VFP Database/Tables as Bank-End.

On our case as a software devt company, we are using option no. 3

Classification of Databases:
1. Desktop Databases - VFP, VdBASE, Access, Paradox, Rbase
2. Server Databases - Informix, Oracle, SQL Server (MS, Sybase)
3. Desktop Databases - Sybase SQL Anywhere, Oracle Personal

You may have more info on this if you have Visual Foxpro 5 Enterprise Development from Prima Publishing where authors explores how VFP fits on Client/Server apps (Chapters 10, 12) and Robert Green's Designing C/S apps with VFP/SQL server from Pinnacle Publishing.