The RT-AC68U is Wi-Fi Certified, but I could not find the RT-AC68P in the Wi-Fi Alliance's new search tool. We tested using our V8 Wireless test process with 126.96.36.199.376_3626 firmware; the most current at time of test. No WPS test was run.
For throughput testing, the router was first reset to factory defaults and Channel 6 and 20 MHz B/W mode set for 2.4 GHz and Channel 153 and 80 MHz bandwidth mode for 5 GHz. A WPA2/AES connection was used for all testing.
The Benchmark Summary below shows the average of throughput measurements made in all test locations. We'll come back later and use the ranker to compare these results with other routers and skip right to the throughput profile comparison.
ASUS RT-AC68P Benchmark Summary
For 2.4 GHz downlink, the 68P's throughput starts out above the other two, then joins the pack through mid-range attenuations and falls off a bit more steeply after 42 dB. This causes it to disconnect for the 63 dB test, where the other two product remained connected.
2.4 GHz Downlink Throughput vs. Attenuation
The 2.4 GHz uplink plot shows a similar pattern, starting out higher at strong signal levels (low attenuations), with throughput falling off a bit more rapidly than the other two products.
2.4 GHz Uplink Throughput vs. Attenuation
The 5 GHz downlink plot shows a much larger difference in performance among the three products, with the NETGEAR R7000 Nighthawk still coming out on top.
5 GHz Downlink Throughput vs. Attenuation
The same pattern is seen for 5 GHz uplink.
5 GHz Uplink Throughput vs. Attenuation
But what you really want to know is how it compares to the RT-AC68U, which you can buy anywhere, but will also run you just shy of $200.
The Router Ranker Performance Summaries for the two products are shown side by side below. The 68P actually outranks the 68U for maximum wireless throughput, mostly due to its strong 2.4 GHz results. But in pretty much every other wireless category the 68U does better.
Ranker Performance Summary - ASUS RT-AC68P / RT-AC68U
All that said, the only reason you should buy an RT-AC68P vs. an RT-AC68U is for the P's significantly better USB 3.0-connected storage throughput. Since ASUS is managing to keep prices for both up near $200, you might as well go for it.