On one of my bikes I am running a Shimano front derailleur designed for 50/39/30 rings but with 52/42/30 rings. No problems.

On another of my bikes I am running a Shimano front derailleur designed for 50/39/30 rings but with 50/39/28 rings. No problems.

If you're feeling experimental, you may find your existing components interoperate just fine.