VPI antiskate nylon string and collar

My Prime came will the AS device. I noticed the nylon sting is connected to a collar that is secured to the arm. I'm appears the collar is adjustable via a clamping nut that could be loosened and thereby alllowing the collar to be slid further toward the back of the arm. Would there be any benifit in the when adjusting AS?
no.  The collar is affixed as close as you can on fhe arm, and behind the spike (bearing).  The arm itself should be adjusted a precisely as you can.  Personally, I found that no antiskate at all is my preference, so took the ring/fishing line off altogether.
Assuming this is the normal unipivot, I believe Michael Fremer measured it with a Wally device and found the best setting was with the ring removed totally, as even the lowest setting provided too much antiskate.  
According to the Wally device, of course.  
From Michael Fremer's Prime review: 

You can try it both ways and decide for yourself but if you are tracking at between 1.75 and 2.2 grams use three O-rings placed at the end of the anti-skating lever. I base that on measurements using the “Wallyskater” device and backing it up with Telarc’s Omnidisc test record that has the best anti-skating track ever.

Read more at https://www.analogplanet.com/content/select-vpi-prime-turntable-and-make-great-choice#JXwo63spZIamEp...
I use the AS device with a SS Aida as per Sound Smith instructions and it works very well. It basically stops sibilance on the vast majority of records. More focused sound. I had a friend come over who had gotten setting it up down.

I also like it because you can loosen up the twist in  the connection wires. We used a blank LP to set it up. We also kept the AS device lined up with the front edge of the junction box so when I add or take away rings the AS Device it is in the same position. That way I am comparing just the weight not the weight and position of the AS Device.   
As you rotate the a/s device on the junction box, it can provide the greatest a/s force to be set variably... As the cartridge moves across the record, skating force changes...some say the greatest force is at the end of the record (the loudest usually), some say its at the beginning where the record is really moving under the arm faster than at the end, and some think the middle of the side is the best solution. The VPI a/s device enables the user to adjust where the greatest force is by the a/s rotation clockwise/counterclockwise on the junction box. When the little a/s arm is at its most horizontal position, the greatest force is applied, when the weight of the little arm is gradually supported by its pivot, the less a/s force is applied. My cartridge tracks perfectly well (no sibilants at all with any record I own) with no a/s. Cartridges do their best when adjusted properly...a very time/patience consuming activity.