HWMPPlus Include client facing AP in mesh?

My network is pretty close to the classic scenario shown in various wiki articles and presentations… A mesh of Metal 9 radios in dynamic-wds mode providing the backbone with a Metal 2 attached via ethernet cable to each Metal 9 to provide client access. The clients themselves are dumb 802.11 devices and are fixed.

My question is…Should the Metal 2’s be part of the mesh or should they be bridged to the Metal 9’s? Are there advantages or disadvantages of each scenario?

Current scenario: The mesh extends to the Metal 2 wlan1 interface. It was just easier to set up this way.

         Metal 9                         Metal 2
 --------------------------          --------------------- 
| WDS                      |        |                     | clients
| ...     mesh1    ether1  |--------|ether1  mesh1  wlan1 | ...
| WDS                      |        |                     | clients
 --------------------------          ---------------------

Alternative 1: The mesh ends at the Metal 9 ether1 interface

 --------------------------          --------------------- 
| WDS                      |        |                     | clients
| ...     mesh1    ether1  |--------|ether1 bridge1 wlan1 | ...
| WDS                      |        |                     | clients
 --------------------------          ---------------------

Alternative 2: The mesh ends at the Metal 9 bridge1 interface

 --------------------------          --------------------- 
| WDS                      |        |                     | clients
| ... mesh1 bridge1 ether1 |--------|ether1 bridge1 wlan1 | ...
| WDS                      |        |                     | clients
 --------------------------          ---------------------