Programmatically its a two part mechanism, firstly to alter the size of one of the buffers, in this case the one that is concerned with the primary network engine, we have at times told folks to use the lower settings due to the attackers being able to make more usage of your bandwidth, as Silicon states its also a protocol level tweak that lets other primaries know that your open for more or less extra traffic depending on the specific setting.
At this time I suspect it wont make much difference to the general operation of winmx bar the caveat I mentioned above.
