Swap in a VS only if the SH fails. The SH is not a bad movement and can go the long haul so if it ain't broke don't fix it.
The click spring is the only thing I'd bother changing as the gen has much softer and smoother clicks. I'm not sure how the Ewatchparts spring is compared to gen. I'll have to get one to try as my ARF still has the original stiff spring.
If you are upgrading the bezel get a gen insert. It's not a big cost and it's easy to source so may as well splurge there.
Don't bother upgrading the bracelet or clasp. Maybe just soften the edges if you like. I have a gen Z serial and an ARF and they're close enough to not warrant an upgrade.
I also dont see any reason to upgrade the crystal as one with AR or a black hole effect is not like gen at all. My gen has no AR and reflects everything like a mirror and I've even used it to check out a girl standing behind me in line.
So come to think of it if you're going to upgrade any parts get gen and slowly go franken