Shawn Hargreaves >XNA (in fact all of D3D and GPU hardware) is focused on 60hz animation, and not designed for either inputs or outputs with millisecond precision.
(note the italics)
Unfortunately game and tech journalism is in on this scam/conspiracy to ruin the arcade and twitch PC gaming experience for good.
I don't recall a single tech journalist using a benchmark for a true keyboard to display latency. (Input to output, that's pretty critical right?)
One could probably develop such benchmark tool on a breadboard with $5 of components from ebay, yet no one in the "tech" journalism has bothered. Maybe they aren't that much into tech or are paid to shut up about this by Nvidia, Intel and Microsoft.
I think it would be most interesting to see a line up of all sorts of PC hardware from early 80s to right now tested for end-to-end latency and jitter in end-to-end input-output.
I would not be entirely surprised if the best performing hardware, as usual, was made in, as usual, in the early 90s, as usual.