I also have the MJ splitter on zci's made out of mdf. I also use push sticks and such. I think with any system you use, if it is tough to get the piece through, that is when you have the potential for problems. Good advice was given on trueing up the board. It's when we rush things that we are in danger. The added benifit, besides safty, is usually better results.
I think blade guards that come with the saw are are good but may impart a false since of security. I think most of us keep are fingers away from the blade. It's when something unexpected like a slip happens that we get hurt. The gard may remind you that it is there but it's not going to stop a digit from going under it if you slip. The paws on the guard are great though for when kickback does happen. Now if I could get a splitter with paws on my rigid that would be nice.