So to do traffic shaping on ePMP 1000 you build MIR profiles on the AP then apply one of those profiles to the SM. Works great.
Now let's say I have a multi-tenant building with three customers and I want to sell those customers 5mb each. Since the MIR profile affects all traffic I either have to cap the SM at 15mb, thereby giving all three customers 15mb of service when they are paying for 5mb, Set the SM to 5mb and hope they don't cause issues for each other, or pick something in the middle where I am again providing them more than they are paying for. Or I have to put three SMs on the roof of the building.
We use VLANs to isolate customers from each other and to give them their own Public IP space. If there were an option in the SM to assign different MIR Profiles based on the VLANs the traffic comes in tagged as then we could reliably cap each customer to the speed we are selling them.
Tagging is handled by a managed switch that sits behind the SM. In UBNT land, we create what they would call a traffic shaping profile for each VLAN that would pass through the SM and this works swimmingly. This is the one feature that AirMax provides that I wish we could do on ePMP.