Yes, SPS was created for bakery's who didn't offer delivery, so that the customer could transport their own tiered cakes. If you can lift it, you can deliver it assembled.
PS that center dowel doesn't really do anything. If your cake is really sliding sideways, the dowel will stay firmly impaled in the bottom board and tear right thru your cake.
That's interesting, many thanks for the advice. I haven't gone down the sps route yet (haven't had the need bc I mostly do 2 tier & have found bubble straws ideal for that. I do have a 3 tier coming up and will be reading through your words of wisdom upon construction)!