IMO only. I prefer the sguare ones and feel that there is less pressure
under acceleration with the square ones (as there is a larger contact area
spreading the pressure over a wider area,hence giving better support) But the
round ones are easier to install since you dont have to go back and straighten
them all out. It's probably more personal preferance than anything. Just MO.
I have had good luck with the plastic square ones.I am assuming that they will flex a bit and maybe eliminate cutting the track if the stud is under alot of stress.When I had to use round I rounded off all edges before installing.Just My opinion and past luck running 12000 miles with out losing any.I also stud on the outside.Also a great amount of common sense as to what a person is spinning on will dertermine how long they will stay in.
i prefer the stud boy ones that are a mix of round and square, it cuts down on the cutting effect that the squares tend to have when they turn but still has the strenght and the surface area to have less flex
Round ... just my preference in that you don't have to worry about lining anything up. I ran Fas-Trac backers this year, and was very impressed with their quality. Their newer round backers have a built in collar/boss which adds support to the stud. Very good IMO.