As Philip already mentioned, make sure your Air Marshal settings don't see the Cisco APs as a threat.
For that go to Wireless > Air Marshal.
Either allow all rogue APs or whitelist the Cisco SSIDs.
Should be able to make it work. But it's not ideal. As you already mentioned real roaming will not work. And what if someone calls with problems connecting to the network, you'll have to figure out which network they're talking about first.
From a RRM perspective what Philip said also makes sense, if you mix them too much it will mess with the RRM algorithm.