Hi Steve,
I get what you are talking about in going from the master computer to a slave computer like an external midi instrument. That is actually a great idea! Looks like you’ve aquired plenty of hardware to accomplish your goals and have a very flexible set up, being able to move and adjust the size of your recording rig at will.
So what the heck are you recording, a full fledge orchestra with that many VSTI’s? 
What kind of music are you recording, a bit of everything?
I don’t know how much you would gain that cpu change, but at the right price, it certainly couldn’t hurt to get you some more horsepower under the hood for heavy processing sessions.