The slider at the bottom has no effect, it was disabled some years ago. But the other option does seem to work. But still, I don't believe there's any definitive way to check. Checking uses up bandwidth & if this is made a requirement would slow the network down considerably. Some people make the severe mistake of thinking browse is a method. But this is simply not true. One minute you can't browse someone, 15 mins later you can browse them & they have several thousand files to share. So ... never think of browsing as a method of checking for freeloaders!!! Browsing is affected by too many factors such as available slots & bandwidth, etc.

BTW my personal testing using the minumum no. of shares, etc. setting did definitely seem to have some effect as to who was uploading from me & what they were uploading from me. Changing it from zero to 25 or 50 seemed to bring out different types of downlders.