Nope - especially if it is a milestone gift. However, we do tend to save those for birthdays when possible. We try to be pretty even handed when it comes to Christmas, but even if someone gets a 'bigger' present, we don't work hard at trying to make ti all even. You get what you get and you don't complain a bit!
I think the cash would be a big hit - and let him really put it where he wants - and on something he might not have shared with you.
Do you still do christmas lists? Even though Connor is in on the secret, we still ask for a list with the understanding it's something to help guide us to shop, not a guaranteed thing. So a list for him might be useful to help, too.