I have attached the universal stud, such as this one, from vendor linked by OP: http://usaknifemaker.com/folding-knife-parts-c-30/other-folding-parts/kwik-thumb-stud-tm-add-on-black-oxide.html, to various Buck folders, and some other, older folders which benefitted from doing so.  There is no doubt the bar-type is lower-profile, and gentler on pocket linings and knife pouches, but the lower profile comes with the price of not being such a sure-fire opening assist, particularly if the user's hand--or the knife--is wet and slippery.  A reasonable compromise is to file/sand a bevel or rounded surface where the barrel of the stud meets the top at a sharp right angle.  A little bit of beveling or rounding will go a long ways, so easy does it.