Although 5Ghz supports faster speeds it's also weak when it comes to penetrating walls. At home although my Airport Extreme is setup for both 2.4Ghz and 5Ghz 90% of the time I'm using the 2.4Ghz for signal strength.
I can't use the 5 Ghz signal from more than about 10-15 feet in my home. Works great within a couple meters. 2.4 works at 200 feet, from my computer desk all the way out to my garage.
I notice a HUGE speed increase with my 2.4GHZ network with my iPhone 6 over my iPhone 4S, but my 5GHZ network with my iPhone 6 is significantly slower when compared to my laptop.
yes, still buggy since imac/macbook with ac chips works with full signal and my iphone 6 is not
and it is strange because only the download is slow, the upload is fine