I wouldn't use them. When you need a splitter, you REALLY need it and flimsy plastic things would not work IMHO. Just last week I was ripping some 5/4 oak with an attitude. I sure was glad I had my metal splitter.... The most popular splitter / guard mentioned most on the wood working forums seams to be the Shark Guard. You can buy the guard, splitter, ZCI or combination of all. I almost bought one, but liked the Biesmeyer better because it just clicks and in removes without tools and I hate gaurds in general. But the Beiz is only for Unisaws.

SharkGaurd…
http://www.leestyron.com/sharkguard.php

I think the gripper would collect dust. Too much trouble to set it up. I make my own push sticks. They are just simple T-handled things made out of plywood with the handle about six inches high.

I also have board buddies, but don't use them very often because I can't use a push stick with them in place.

Really, but best defense is to carefully set up the fence to run about .005" out of parallel to the blade and just good old common sense. I set my table to blade with a dial indicator. I made a simple jig out of oak that is a T that the dial mounts to. I set the blade to miter as close to perfect as I can, then set the fence to the right miter to be .005” out in the rear. I also have a 10” plate that I use, but you can get away with using the blade. The plate can also be used as a sanding disk, and that’s usually what they call them when you go to order one.