Everyone's needs are different. You need to do what is right for you. I'm disabled so don't work any more. I have the time and motivation to work on my own machines. Not everyone does.
Your situation sounds far different than mine. You have what sounds like a decent paying job and the long hours that come with it. For you it may make perfect sense to have fewer machines and pay for any work that needs done.
There's also something to be said for a house where you're not tripping over machines.
Sewing machines are fairly easy to transport and relatively inexpensive. It's a combination that makes it very easy to acquire far more than you have time or space for.
I say it sounds like you've put a lot of thought in this. Go ahead and thin away. I think it's better for collections (or any belongings) to have use and/or meaning for their owner. They shouldn't be a burden.
Rodney