The exemption is in the first instance on the employer having to operate PAYE/PRSI on giving the voucher - so the company doesn't have to treat it as pay.
I'm not sure about the individual taxpayer, I can't find anything to support or refute the point about the amount needing to be returned by the director on their own personal income tax return. To be fair though, if in the course of an audit, you end up in an argument with a tax inspector about whether or not this €250 voucher was taxable, you'd have to be dealing with a pedant of the highest order.