Interested in hearing other's thoughts on this.
Initial reaction is: depending on the amount - and what his total annual earnings are - try and stick to Ireland, as it is a very low tax country. For illustration, the Lib Dem's radical tax reform would give people an annual tax-free allowance of €12,000, compared to what we've enjoyed in Ireland for the past few years, €18,000.
If he's already up beyond €35,000 in earnings, the marginal rates are probably quite close.