Hey Bill, I know our situations are not the same, but here goes:
I started collecting cards in 1965. Years later I decided to collect that set again, along with T206s. I've nearly completed re-creating that first set. I know that if I sold it I could buy another Uzit, or upgrade a Cobb, but that old set means too much to me to get rid of it.
When I look at them I can still remember opening packs, hoping for a Mays, Mantle or Koufax. And somehow every pack seemed to contain another Gary Bell.
Anyway, if you get the same enjoyment from your modern cards, I recommend keeping them. But if it's about money, sell them and get a nice Ruth or whatever.
And let us know what you decide.