To quote a friend, it depends. 😃
Some are 100% against it and prefer to use proper design to 'persuade' clients to connect to 5GHz. By that I mean by using a 6dB difference in power between 2.4 and 5Ghz, which tends to be the magic spot so that cell sizes match and the end-user doesn't hear the 2.4GHz much louder. Client devices have a tendency to be stupid, and the louder the RSSI is, they cling to it.
The theoretical 'pros' are that it will get more clients onto 5GHz and that is usually what you want since 5GHz usually is much cleaner, less noise, faster throughput etc.
The 'con' however is that it is an imperfect solution to an imperfect world. Clients send out Probe Requests on 2.4 and 5GHz at the same time. The method it uses to accomplish this is by ignoring the probe requests the client sends on 2.4GHz (usually around 3 times) and by doing this, it hopes that the client will see the Probe Responses on the 5GHz side and end up connecting to that.
Doesn't always work, and so sometimes it might cause some 'thrashing' and and the end of the day you want your wireless to be as seamless and as stable as possible.
My solution, in case you noticed by my screenshot above, is to use dedicated SSID's per-band. My corporate networks are 5GHz only. The guest network we have, is dual-band with the band-steering enabled and for the most part it works, have not noticed any 'obvious' issues.
I would prefer to use seperate SSID's for guest, the problem though is that it just doesn't look 'clean' and now your relying on end-users to make the right choice.
Random Example:
Starbucks <---- one SSID, clean, simple, with band-steering
vs
Starbucks <---- 5GHz only
Starbucks Legacy <---- 2.4GHz only (Legacy being the word I"m using to reflect 'slower' or 'less optimized'.)
It achieves the goal, but you might run into users choosing Starbucks Legacy even though they have a 5GHz capable device.
So for non-critical SSID's like guest, I will use it. For business SSID's though, I will use a 5GHz only SSID and it takes all concern out the window.