Using multiple SSIDs in SM for failover

We have 3 APs all aimed in about the same direction (2 20Mhz and a 40Mhz). Customers are spread out across the three.  I am thinking that putting the other two SSIDs in each SM might be a good idea for failover. If the AP they are normally connected to goes down, the SM would attach to the next one on the list.  Not ideal for bandwidth management but better than off-line clients.

If the 1st AP in the list goes down and they switch to AP2 in the list, what causes them to go back to AP1 once it is back up again? Do I need to reboot the SM remotely or does it check from time to time?

Unfortuantly, there is no automatic or timed way to get an SM to re-associate to a primary SSID after it has connected to a secondary/other SSID. The SM will need to be de-registered or rebooted in order to connect back to the primary SSID. I believe there's a request in the 'Ideas' area of the forum for such a feature. PMP100/450 AP's and SM's already have this feature.