Even if you change it dynamically, what will you change it to? The thing about the way IE works is that it will spawn new processes based upon an algorithm based upon system resources which may not be static from one run to another. So, when you run your tests, it may work to update the process from 1 to 2. But the next time you run it, it may need to be 1 again, or 3, or something else. It's not necessarily easily predictable (although, I'm sure if you spent time, you might be able to do it).
In the meantime, the registry edit does not change the behavior of IE when it comes to executing applications, serving up web pages, etc. All that feature does is allow for IE to recover from a crash if one page crashes so that the user does not lose ALL pages they are currently working with. I still highly recommend making the registry edit.
