[Plugin: WooCommerce – excelling eCommerce] SKU – Curious :P

I am trying to work out wether using SKU is “necessary” and/or useful with downloadable products?

What are the pros and cons of using it if any — possible “real life” scenario(s) and what not please?

Thanks

http://wordpress.org/extend/plugins/woocommerce/

[ Please do not bump, that’s not permitted here. ]