Here's what I've done that currently has resulted in about double my WiFi download speed for my MBP. (Before making a change in my Airport Utility setup, I had the AE 2.4GHz set to a specific channel and 5GHz channel set to Auto.) - Now, after testing several alternatives, I've found that increased WiFi download is being achieved by setting 2.4GHz to Auto and 5GHz to a specific channel.
While under my AE Wireless Options tab, the 5GHz network name option is checked (and the name is only different by having "5GHz" in the name), my WiFi connection, for my MBP (as well as all other wireless devices), is connected to my named Network that I've used for years.
So, I'm not sure if I've actually achieved what you suggested. But, the above setting has, at least so far, resulted in much improved download speed for my MBP, which was my principal objective. (My iPhone 6 & iPad Air continue achieving excellent download speeds.)
Any followup thoughts?
