You'll have a problem with .ACD files, because those files keep track of online data, which naturally changes over the course of time, but can be ignored when comparing for differences.
If you save your .ACD file to a .L5K or .L5X format, these are native ASCII text files, and could possibly be integrated into your VCS. The Rockwell compare tool does essentially the same thing -- exports the two ACDs to L5Ks, so that it can compare them readily.
Heck, I've used DOS's fc.exe to find differences between .L5K files when desperate.