I m afraid you are perpetuating the myth humans can only percieve a fixed FPS rate.... :(
source If you want to search visual acuity in the journal of neuroscience im sure you will more research verifying this.
As for having higher frames be relevant. Each frame, for CS as an example, is an index where the game can take input from the mouse / keyboard, and logs your models xyz co-ord, and sends that info to the server which compares it to the other data from other users, and then applies lag correction based on the time stamp of the data and what it correlates too.. in a rough form.
Simply put, the more frames you index, the better chance the data you send to the server registers as data before the other player shot. Some players use the lag correction aspects to their advantage by skewing their settings, but all things being equal, it is better to have more time indexes to send.... its simple sampling, you have a higher sampling rate of data then your oppenent, your data based on Did A shoot first, chances are it will be a more accurate experience, as we are not robots, we do things like PREFIRE etc, based on what we think will happen, and higher sampling makes all of this more effective.