In a London brick Victorian flat, you tend to need more than one wireless access point. We have two: both 802.11ac, one from Netgear, one from Buffalo, both with 2.4GHz and 5GHz connections. My Lumia 1020 sees the 2.4GHz radio in our access point with more bars than the 5GHz radio in the same AP. That's to be expected; the AP is in the next room and 2.4GHz has a longer range than 5GHz.
But I found myself wondering which connection I should use. The 2.4GHz connection offers lower bandwidth, but with better signal strength; the 5GHz connection has higher bandwidth, but will the weaker signal strength mean I get the same or even a slower connection? I fired up the Network Speed Test app from Microsoft Research, tested the speed on one connection (running it three times in case of anything else on the network that might affect the results) and then logged on to the other connection and tried it again.
The results did vary between the runs, but both the average and peak results showed better bandwidth from the 5GHz connection, even with the lower signal strength; up to 18Mbps rather than between 7Mbps and 10Mbps. I saw the same speeds on the Lumia 1520 on the 2.4GHz connection, so the faster processor in the phone didn't affect the throughput, but it didn't see the 5GHz connection at all.
With that kind of a difference, if you have multiple access points or connections visible, you may want to run your own speed test to see which is faster.
Interestingly, Windows Phone tended to pick whichever network I had connected to last, whereas Windows 8 is more likely to switch if it finds a network it thinks has better bandwidth.
Notebooks and laptops have higher-powered wi-fi chipsets that give you more bandwidth than phones and tablets, so switching to a better connection may make more of a difference on a PC. Or maybe that connection managing logic is something that will move into Windows Phone in a future version, given that it's based on the same kernel.
These are the kinds of alignments that will get easier if Microsoft rationalises the number of Windows versions it creates.