When you have these discussions, your wife needs to have your back in the discussion, make sure he understands that all choices are made by the two of you and not just you. 2 against 1 is better odds.
His wife can have whatever opinion she wants, there's no reason to expect she agree just because she's married, unless I'm misunderstanding you?
OP, it just comes down to how much you care about his opinion and how reasonable you think he is. You have more experience dealing with him than anyone here...I assume! Maybe try pointing him to some computer geek forums, maybe he'll be more open to talking about it with people who can speak in his own technical language?