USB hubs didn't affect the latency results. I even strung 3 together and got slightly (0.01-0.02ms) improved results in some tests. But Fast USB polling absolutely did affect latency with 2-4ms improvements to the average in my tests.
The controllers I tested:
- Original XBox Controller S - Native USB but just a 7.2ms avg
"Sega" (probably a knockoff) Saturn-style USB controllers (marked SLS ISS-5001-01 on back) - 0.8ms average - nice
No-name translucent blue 2-port PSX-USB adapter - 13.4ms avg
No-name black 1-port PSX/PS2-USB adapter with guitar switch (for using Guitar Hero PS2 controller on PS3) - 9.9ms avg
8BitDo Zero w/CSR8510 - 14.1-14.2ms avg in all the modes I tried . Similar latency to other 8BitDo Bluetooth controllers
Mayflash SS/N64/PS2-USB adaper - the worst average 17ms (N64) 14.7ms (PSX) and 12.6 (SS), and VERY inconsistent, with frequent 60+ ms delays
* All adapter tests were done with genuine original controllers