ShipWire is focused exclusively on high-volume clients that require multiple international warehouses
If you have high international monthly volume, ShipWire (and other international platforms) may be a more suitable fit for your business.
If you are running a small - mid level eCommerce business, SPNS is better suited to meet your needs
With that said, premium services don't have to come at a premium price. SPNS provides door-to-door parcel tracking and courier follow to minimise loss, and offers tailored shipping partners to suit your products - as part of its standard package.