Difference between C166.EXE version 3.12 and latest

We have been using the Keil compiler for about 7 years now. We do not use the uVision IDE (even though we paid for it), instead we use the MSDOS executables C166.exe, A166.exe, etc... We have always used version 3.12 of C166.EXE which is dated 4/27/1998.

The compiler executables are tied to multiple different projects and stored in the bin directory with the project. For example: C:\Boat Controller\BIN
Thus on one computer, there may be multiple copies of C166.EXE, each stored with the appropriate project. It is a trivial process to install the source code and build it on a computer that did not previously have the project on it.

This has worked very well for us over the years. Recently we implemented PEC functionality on a controller with the C167CR processor. There is a known errata with the processor regarding the PEC. A workaround solution was applied in software but it inflicts a performance penalty (and is ugly to boot). Keil's newer compiler has a fix for this problem. We would like to have the fix for this processor because it would lift the performance penalty of our fix.

After all that blather I will now try to get to the point. I spoke with a keil tech support person today who told me that the newest versions of the Keil compiler can only be installed to a single directory. He told me if I made copies of that executable in other directories, I would only get a limited version of the compiler. This would not fit in very well with our current practice. As he didn't even know what PIF files were, I didn't have a great deal of confidence in his assertion. Can anybody tell me definitively if I can move the C166 executables into any directory I want after installation?