I have had the GoG version for awhile. But, I only installed it properly (have many installs with various executable etc. files) on my old machine that doesn't need the Vista Fix . . . Until NOW.
So, I wasn't using the GoG executable file with dgVoodoo.
Turns out that when patching the blurry texture issue, GoG includes a custom dll file (d8tx.dll) that is called by the GoG version executable. Thing is that dgVoodoo also includes dll files (not an expert, but I believe that only the D3D8.dll (DirectX) one is actually needed, the other two are for Glide and DirectDraw) that need to be placed in the same folder as the RT3 executable.
There is some conflict between the two: d8tx.dll and D3D8.dll, and deleting d8tx.dll results in crash of "failed to find ...". What ended up working was deleting d8tx.dll, taking a straight copy of "D3D8.dll" that dgVoodoo 2.54 (latest version at time of writing) uses, then renaming the copy to "d8tx.dll", and the GoG executable is working under dgVoodoo.
Please be aware that the GoG version is the most up-to-date version that is ready to go (major issues have been patched successfully) which is why I recommended it over the Steam version, just that the dgVoodoo** solution is better than the "Vista Fix" ever was (solution used by GoG) and this is currently the way to get the best possible game for people who don't want to fiddle a little (dgVoodoo is pretty easy setup).
**Notes on using dgVoodoo (see this thread), needs to be setup with video RAM at least 128MB (Edit: read following posts, previously suggested limiting to 512MB) to safely avoid random low texture objects, if Graphics solution enables high 300+ FPS while doing a train ride etc. may need to use option to Force Vsync to avoid skipped frames. Known down-side: screenshots don't work in full-screen mode, I use FRAPs.
Here's an illustration of the most obvious differences between having "Hardware Transformation & Lighting" disabled (Vista Fix) vs. using dgVoodoo.
Water reflections are broken:
whereas with dgVoodoo:
Price map gradients:
compared to the detail with dgVoodoo:
This is not only cosmetic, reading the price map accurately is important at advanced play levels.
Note: there are rare machines which use graphical solutions that will run the game out of the box with Hardware Transformation & Lighting un-checked, in those cases price maps should be normal already, however sometimes dgVoodoo will allow water reflections. dgVoodoo seems to help performance, but so far nobody has attempted a test on machines with benevolent graphical solutions.