Here’s some food for thought when looking at WiFi related issues. Are dual band routers the best solution for you? Or should you stick with 2.4GHz – all this depends on may factors you need to consider.
The 5 GHz signal, being a higher frequency than 2.4GHz, will drop off more dramatically with distance and it will not penetrate walls or other obstacles as well. With that being said, that can impact any speed advantage and actually make this the slower alternative. So ideally you would have to be closer to the wireless router with minimal obstructions, which is often not the case.
The 5GHz frequency works on the newer Wireless N (and very old Wireless A) but does not work on Wireless G. Wireless G is a 2.4 GHz mode only. That means that if you have a Wireless G/N capable router with a mix of G and N computers or devices in the house, choosing 5 GHz will cause any wireless G only connected computers or devices to immediately stop working. On the more positive side, the 5 GHz is less likely to run into interference issues as other
electronics in the area are most likely using 2.4GHz.
My final thoughts are I would stick with 2.4 GHz unless I was simply unable to overcome a source of 2.4 GHz interference, then I would give 5GHz a try.