I think you will... USB is faster i believe...but i guess it depends on what type of game your playing if it will make a difference. If not used for FPS games I don't think it matters. I play delta force and I do notice a diffence especially when knifing.
I read the article you posted and now im a little confused when I test both my mice 1 with ps/2 the other with USB using mouserate I get a higher sampling rate with USB about 200hz avg...whereas with ps/2 I get about 120 hz avg?? It appears that using USB connection gives a higher faster sampling rate isn't this higher rate going to be better in FPS games? or am I mistaken?