Allow me to sync an addressbook without syncing birthdays.
I have a Fruux addressbook that I use for work. It has tens of thousands of addresses in it, and most of them have birthdays.
I also use iCloud's address book to track my personal contacts.
On my iPhone, it's all or nothing when it comes to alerting me about people's birthdays. So in order for it to remind me that my cousin's birthday is coming up, I also need to let it remind me that 10,000 business associates' birthdays are coming up.
I'd like it if I could tell Fruux to not sync birthdays, which would solve this problem. Heck, maybe it could even be more robust and let me decide which fields to sync on which devices.
That is not really possible unfortunately. If a contact has a birthday, we’d have to effectively discard it. As we’re doing “sync”, we’d end up deleting information on all of your devices, which would be very bad.
What you really need is a way to tell your device (iPhone/Mac in this case) to “don’t create a virtual birthday calendar from this address book”. Unfortunately this feature does not exist yet on Apple devices. Whenever they come across a contact that has birthday information, it is added to the virtual birthday calendar (which is fed not just from a specific address book, but instead ALL address books that the device has access to).
Might be a good one to also report here:
http://www.apple.com/feedback/