Did this issue ever get fixed? Currently I have to run the original version from the cd-rom to get config.dat changes to take, then switch back to the 4.50 version or the expansion pack version.

The "Mercury" patch does this. It just sets the "Emulate Get Free Diskspace" for the nfshs.exe .(It´s included in the SP/Ep Pack.;) )
There´s no patched nfshs.exe. Do you plan to make another great patch ?

My fault, I had created my own .sdb file, but had used the cd-rom nfshs.exe instead of the 4.50 nfshs.exe. The compatability fix apparently checks for version and name strings and file size. There's also a checksum, but it doesn't seem to be related to the content of nfshs.exe except for the id strings (I can use a collision always on version in addition to the expansion pack version), so various patched version will still work. At least I rememberd I had to run a race (at least wait until the countdown so a replay is saved) in order for config.dat to be created or updated.

I also named the fix "nfshsxp" instead of "mercury".

If interested, it's here in a zip file:

http://jeffareid.net/nfs4/nfshsxp.zip

I also have a pair of these for NFS2-SE, for nfs2sen.exe (standard version) and nfs2sea.exe ("3d" version). For NFS2-SE, 3 fixes are needed, "CorrectFilePaths", "EmulateGetDiskFreeSpace", and "GlobalMemoryStatusLie"

http://jeffareid.net/nfs2/nfs2sexp.zip

you have a NFS4-CD install RC + EP v1.41 (is all in)