In reality, I can see both views and can't fault anyone for either way. I highly recommend choosing one of the methods though.
I was forced to choose one for the pure reasons of standardization, realiabilify and support.

Several years ago, after deploying wireless in a new building which housed over 700 laptops, I noticed that band select did not do what I hoped.
I had laptop clients connecting on 802.11b/g/a /n.
It was oddly enough about 150 clients on each one. The throughput difference was obviously all over the board. I had the clients managed by an MDM and decided to lock the configuration to 802.11 a/n. With the high AP density, I wish I had the choice to lock it to 802.11n only. So devices continued to connect to 802.11a.

During an outage caused by a bug, it was simpler to have people change the client setting to change bands than it would of been to create and connect to another SSID.

I also was told by the both client teams ( IT and Biomed) , that the one SSID was easier to remember and configure. I did have to add another SSID for clinical devices to enable segmentation.

I can see adding a 5ghz SSID could remove the likelihood of misconfiguration of the client.

End user experience and support teams are relying on wireless expertise to help them remove the client/band issue.

The first few times you get a call about client disconnects and you see the ping pong effect between 2.4/5,you will decide the dual band feature is more of a support/reality nightmare than it is an advantage.

Good luck !!

Jim