If he is a fanboy for mac, then this will be a bumpy ride. The OSx version quirks will soon be forgotten when the first glitch is encountered and he will long for the old days.
That said, if an open mind is kept he may find new things to like not avail on the mac side. Hard to say but when spending this much money you need to be sure.
The OS shapes our experiences and IMO this will be hard to overcome given the above description.