>They don't have any problems now if two or more developpers are working on the same VCX, given that they do not work on the same class. With source control, you can't check out only one class inside the VCX, you have to check out the whole VCX and no one can update any other class inside it while you are working with it. That's their main concern. I have given up VCX for classes other than GUI (I use PRG classes) for this reason and because it's easier to do a file diff, but they allready have a lot of VCX classes and most of them are GUI related (mainly all their forms are VCX based).

VSS is set-up by default to only allow one person to checkout a file at a time, but it can be configured to allow multiple checkouts. The only downside to this is that you'll have to worry about merging changes during check-in (but if people aren't making changes to the same classes like you've said, it shouldn't be too bad). Considering this is how other source control systems like CVS work, I think this is a reasable alternative.

Given their existing "source control" system, I think this would still be vastly better.