Actually those aforementioned payments are quick. These types of payment don't delay your delivery unless you are sending close to that vendor's cutoff time.
Now the next part is tricky. While there is a good chance that if you send payment early in the am that you will receive the very next day. There's an equally good chance it will come the following day. There really are not any guarantees when it comes to ON delivery. If you are lucky, it will happen but I wouldn't want to depend on it.
I think it's only worth the extra $ if you really are in a pinch and hope to see it ASAP. I get upgraded to ON quite often even though I rarely pay for it. So to me, not worth the extra Dinero.
PS I believe the mg form says it is delivered in 10 minutes