What problems should I anticipate if I prefix order IDs with alphanumeric characters?

Question

My client would like to prefix order IDs with descriptive multi-store abbreviations such as WS00000000 (Wholesale), AFF0000000 (Affiliate), RE00000000 (Retail), LS00000000 (Living Social), etc. Its purpose is to make communicating orders through phone support and fulfillment more efficient. Certain shipping rules and order history can be deemed by knowing the origin of the order.

I read another case of a developer attempting it on older versions of Magento as seen here:

http://chilipepperdesign.com/2009/07/09/changing-magento-order-invoice-and-shipping-numbers/

As I assumed, you would need to update all fields storing the order ID from integer to text. I understand that this might complicate upgrades but if I can turn this process of conversion into a script then I can reproduce this on future installs. What other unforeseen problems should I anticipate? Thank you.