Please Tell us NOW What You're t hinking for Marksman Item Rework!
Because I'm skeptical. Critical strikes.
Critical STrikes is the single reason why creative items like Zephyr or Essence Reaver never see play.
"Zephyr no I need to build PD or SS second because muh crits" "Bloo no I need to build IE first and BT is better anyway, especially later when mana is less of an issue."
And both PD and SS have outrageously efficient build-paths on the way that all involve critical strikes, and useful combos, such as attack speed, move speed, or extra income.
There's no getting around the absolute power of Critical Strike, and any item that includes it efficiently will immediately beat the rest, even if other items like Zephyr include other stats efficiently (50% AS, 10% MS, 10% CD aaaaand Tenacity??? Cool... oh wait, NO CRIT).
Let us know hwat you're thinking and how you plan to balance around this.