The part that's harder is that particularly with #2, I'm just a bit more tired, and he needs a lot of energy. It's not drastic, but I notice it.
The part that's emotionally harder is that I'm sad I won't be there when my kids are approximately my age. I'd love to be around longer to help if they have kids, etc., but statistically, I don't think it's too likely. I lost my own mom two years ago and that was very hard. Barring some advances in health care, my kids are likely to lose me in their 30s-40s as well. Losing a parent is never easy, but I think it would be easier a little later. My kids only have one grandparent left and I wish they still had two.
The part that's easier is exactly what you note: Life is pretty stable. We're financially sound. We've had years of growth and therapy to learn to communicate well and have a healthy relationship with each other and our kids. We can afford to support our kids well, be that with high quality daycare when they were young, or an emergency mid-year school shift (that was interesting), or medically, or whatnot.
Lots of tradeoffs. I plan to make the most of my time with them while they're still young. There's no clear answer on the balance other than doing one's best.