Testing was done with firmware 0.9.1 0.7 v002d.0 Build 140624 Rel.55965n, and iPerf used to determine the maximum wireless speed at three locations: the next room, immediately upstairs with some furniture in the way, and one room away from immediately upstairs.
The wireless client used was an Asus G550 laptop with a 2x2 Intel AC7260 wireless card, as an indicator of average performance. Each WLAN is set to WPA2 personal encryption and a clear channel is chosen. Where possible the highest channel bandwidth is chosen, either 40MHz or 80MHz depending on the wireless standard. Where appropriate, transmission standard is set to 802.11n or 802.11AC only.
Due to the variable nature of wireless and surrounding WLANs, each unit was tested multiple times at various times of day to achieve a best case scenario performance value. Your own environment will see different results.
The lower-specced D7 matches the speed of the AC1750 rated Belkin AC1750DB, but gets left in the dust by the Fritz!Box 7490 and D-Link DSL2890-AL. The rest of the competitors are all AC1900 rated.
The D7 is competitive even with the top end of town in 5GHz, pulling our two highest results in the first two locations.
The D7 brings in high level AC results in line with the other AC1750 and AC1900 routers.
Storage was tested over gigabit LAN with a SanDisk Extreme NTFS formatted 64GB USB 3.0 drive plugged into the fastest USB slot, transferring a 100MB file via SMB.
USB performance takes a hit compared to the D9, and is a long way behind market leaders Asus and Linksys.
TP-Link's D7 offers good performance for a small price -- the competing Belkin AC1750DB offering fewer features for a higher pricetag. Australians may wish to spend a little more for the D-Link DSL-2890AL to beef up their 2.4GHz performance, though.