Hi,
The captive portal in the controllers is limited, also the amout of guest accounts.
I would advise to use ClearPass (best practise, a seperate one in the DMZ). With ClearPass the captive portal has many features and different looks. Also the type of guest account can be different and has more options on ClearPass.
You can use multizone if you are running ArubaOS to setup the guest part with controllers in the DMZ.
Not really a document, but some differences.