I agree, metric units are quite impersonal. The only "metric" saying I can think of right now is "метр в кепке", referring to someone very short.
Nothing prevents Russians from using expressions, mentioning traditional Russian measures, though: "пуд соли съесть", "косая сажень в плечах", "писать аршинными буквами", "бешеной собаке(корове) семь верст не крюк", "Мал золотник, да дорог", etc. You must have heard some of them.
PS. "Give 'em an inch and they'll take a mile" - We'd say: "Give him a finger, and he'll bite the whole hand off".![]()