Changing it to a single name for both networks leaves my iMac always connected via 2.4GHz and no obvious way to switch to 5GHz.
I can't say that this configuration change will help for everybody - I'm just reporting what I'm seeing.
So now I keep separately named networks and can usually connect at 450 mbps (mbp) or 150 (mba). At least I believe that is the case, I can double check at home.
* Connect to the 2.4Ghz network
* Hold "Option" and click the wifi icon in the top menu
* Note the "Transmit Rate"
* Repeat this for the 5Ghz network
When I first setup my Time Capsule I noticed that my Mac often times was attaching to the 2.4Ghz network. At that point I separated the networks and did the above.
Low and behold, each time the Mac picked the 2.4Ghz network it did so because it had a higher transmit rate than the 5Ghz one in a given location.
Now I'm on the 5GHz again I seem to be getting a more consistent 450Mbps link speed although actual throughput seems the same.
I think I might just leave it on fully auto now, it seems to work pretty well.
This is a classic case of someone geeking out over settings and over-optimizing themselves into a corner. Hence the last line of the article, and an excellent moral.
Saying that, I see no downsides to leaving it fully auto and I think I'll leave it at these settings now.