FWIW, the problem with FedEx Smartpost is typically in the transition between FedEx and USPS (who makes the final delivery). When I get things, the FedEx side typically goes very quickly, but then I wait forever for the USPS side of the equation to get the package to my town and make the final delivery.
Sometimes, I feel like FedEx drives past my town to deliver to a "designated" USPS receiving hub, which then ships it back past my town before it eventually gets to me. However, since most things I buy from MD take 3+ wks just to ship, the few extra days in Smartpost land isn't a big deal to me (I'm already waiting).
In any case, I'm sure YMMV depending on where it is shipped from and the final destination.