I don't have a direct answer for you but as someone who hires for my own business, I hate unlimited vacation bullshit. It puts the pressure on the employee to decide what is reasonable and also the company gets away not paying any minimum un-used vacation time (which employees deserve).

I would have a "minimum" vacation days policy if we do use unlimited but then it defeats the purpose for employers who want to NOT pay for any un-used vacation days. Just do 4 weeks and be done with it if you can afford it.