You have made some interesting modifications and improvements Leo. I had already planned to clean up the "path to BC" determination, recognising that most users will run the executable from the default installation location. Your code for interrogating the registry is not something I have ever come across before and looks to be a very useful snippet to keep. I also like your archive handling and use of BComp, if available, to open in tabs.
My logic for determining what to compare under various circumstances is driven by the way I typically use BC. Your logic is different but I have no doubt many others will prefer "Leo's way". I'll add a link at the top of the thread pointing to your code and description. I certainly plan to incorporate several of your improvements into "my" version and will likely post an update once done and tested.
Regards (and thanks), AB