Thanks for confirming that this (smartroam problem) is "normal".
In my case it seems like the iPhone gets smartroamed back and forth between APs several times, and then gives up on WiFi "permanently". (or until the device gets locked/unlocked, etc.)
There are courtyard areas between buildings where this often happens.
I've had this user complaint many times, and mentioned it to tech support many times without hearing any explanation/confirmation.
smartroam solves serious roaming problems for me, but if I use it, I shouldn't expect my iPhone devices to work...