I finished the top a little while ago and finally got around to attach the magnets to the top. There are a couple of issues that I found where this tip does not work well for me. The tip works great for 3/8" thick and less material. I generally work in 1/2" and above. I do a fair amount of stack cutting also. The little knob that holds the top of the blade gets really close to the part when raised 3/4". It will not damage the part but it does not feel good when your finger runs through it. A 3/8" and thinner piece would not have this is not a problem. The part in the picture is 3/4" thick.
My basic design was to have a 1/2" piece of plywood with a 1/4" piece of plastic attached. I know the picture looks like the top is warped but it is not. I had seen others put a piece of thin board on their tops to reduce friction, others wax their tops. I had a piece of scrap plastic so I used that on top. Underneath I used rare earth magnets. I was not sure how many I needed so I started with two and that was all that was needed. They hold the top down just fine.
Although the tip does not work for my purposes it was a good tip. However, I learned why people put thin board to reduce the friction on the plate. The plastic I had is used on production tables because of its low friction. It made a huge difference in cutting tight corners and small areas. The past few times I have been using the top risking minor pain to my right index finger because I like the plastic top so much. Now I just need to figure out how to put a removable 1/4" plastic top on the saw for my fingers.