Acl repro armor isnt always historically accurate, nor do they always use historical padding. It varies maker to maker, but its more of a safety concern.

That said, 11th century arming garments isnt really a traditional plate harness, given that its pique was 14th century and going into 15th and 16th. Its not suited for acl either, as the garb will most likely be chainmail chausses, hauberk, and full helmet. Chain mail is not the best when it comes to blunt trauma.

Take a look at tobi capwells work. Theres also many books on the reproduction of historical armor. The only thing i would buy off shelf would be chain. Otherwise, go semi custom or full custom with a company like art of steel. Theres a dozen makers out there i can point you to for 14th century armor, as acl is mostly that.