Actually, I've been thinking about doing the same thing.
But i don't know much about emails.
I go through the filter every now and then to see which services are still using my old address and change them to use the newer one.
It's also a nice way to find out how horribly some services have f-d up the change process. One had a non-working change email button and the CS rep just deleted my old account and told me to create a new one.
One just plain doesn't let people change their email. At all.