Good morning.
The balance-bands option for you would likely be a good idea given what you are focused on providing.
Why do I say likely? Because: Your mileage will vary with which setting to use in steering, based on your environment. Remember, your environment is not just your AP deployment but your clients, client capability mix, and in all likelyhood, also your neighbours (and their networks and general interference, such as they may be).
Balance-Bands was an option that was implemented after the initial release of the Aruba band steering feature to provide more flexibility for all deployments. The goal being to make use of both bands 2.4 and 5.0 GHz, while still delivering clients up to 5.0 GHz when/as appropriate.
In your case, with a single client type that you are focused upon, and that client type having a rather limited radio capability (150Mbps) when operating on either 2.4 or 5.0 GHz.
If we assume both channels have similar utlilzation in your environment, then the iPad Mini will deliver the similar results on either band. aka. IMO there is no 'harm' to proceeding with balance-bands in your case, and with it's ability to 'spread' out the clients across different radios as balance bands will do, you will set yourself up for a potential performance increase with less clients sharing a given channel. Positive! ;)
JF