I didn't read everything so maybe it had already been say, if not it might interest some of you !
I came accross this software when I bought my Bloody keyboard. It's named "KeyResponse PK"
In the intense gameplay, millisecond often determines the winner. You may not know how long it will take the computer receives the data after pressing the key of your mouse or keyboard. This time delay is commonly known as "Key response". This software is particularly made for the gamers. Through the simple PK face, gamers may explore the truth of the real key response of the gaming mouse and keyboard. Besides, gamers also may get full understanding of the key design difference from the dartboard explaination so as to avoid spending lots of money but obtaining the low response inferior products.
It works both with mouse and keyboard and it's available here :
I didn't test it yet but I think it worth to give it a try