hi casie,
My wife and I took the same decision some months ago. she gave up work to mind the kids. we switched the rental property to int. only. The extra cash (c350e/mnth) makes the ends meet and, all going well with rental markets/yields etc., should do so for the duration that she decides to stay at home.
As was said, the downside is youre not clearing the capital on the house AND/OR youre not putting the extra cash into a pension so your future might not be as comfortable, but what it gives you is the leeway to make the lifestyle choice of staying at home to mind the kids. So to us, it was a matter of either sacrificing lifestyle now for one 20 years from now, or having the lifestyle we wanted now and possibly sacrifing the future one, but thats a decision only you can make for yourself.