I had to look into it, since I read Subs post
so let's see what I found so far and anybody can chime in.......According to Mike (LDH) at Kyle Racing, the link is most beneficial for riders under 200 lbs.
Also, the SP1 had a much more progressive link ratio than the SP2 (which was changed as part of the SP2 improvements).
The link makes the link ratio more linear, which is why it is more noticeable on the SP1 vs SP2.
My bike had the link installed when I bought it, and since I too weigh over 200 lbs, I'm installing the OEM link as a test.
Also, since the Kyle link alters the link ratio, a slightly stiffer spring is needed to equate with the OEM link.