Time to leave?

LP came up with a news today. He has got a good offer : from a midsized s/w dev. firm with a good position and a good salary offer. (approx. 40% hike from his present package).

As a manager, i need him and treasure him, inspite of my stingy appreciations and raising my bar of expectations everytime. But as a friend i want him to prosper in life and to go places. Also, as a manager, i don't want to block his career progress. Well, Not an easy decision to make. But for sure, i've got to make his exit a smooth one with his credentials intact and a win-win for both him and the organization.

Time should tell...