The 2760 only supports 2.4GHz wifi and doesn't support 802.11ac. 5GHz is useful to improve wireless download speeds in areas with 2.4GHz congestion and 802.11ac also improves speeds. 5GHz is pretty much defeated by solid walls though so isn't always the answer.
It also depends on what wireless devices you are using. On older Macbooks, 2.4GHz only supports a maximum rate of 144Mbps whereas 5GHz runs at up to 300Mbps. This makes a difference even on FTTC connections.
Additionally, an existing router could be used as just a wireless access point which reduces the cost.
I did try a 2860n+ which has dual band and found the 5GHz to be disappointing. That may have changed with more recent firmware updates. That's at a site I no longer maintain.
get a significant wireless improvement on the 2860n by upgrading the antennas.
Thick walls are going to be a problem whatever wifi you have. Experimentation to find the best homeplug/access point combinations is really the only answer.
Edited by caffn8me (Wed 28-Sep-16 01:41:37)