The 1/2 inch up cut is the most important for making MDF tooling, and cutting several rib blanks all in a single pass. This bit did the rough cut of all blanks and lightening holes in ribs before the flange was bent.
The 1/4 inch was only used while making some of the pocket ribs.
Routers are dangerous. Metal -hot metal- goes everywhere. The upcut pulls chips into the router and away from you. That is good for you and bad for the router. I modified my router so that the holes were blocked. I also used a vacuum to pull out as much as I could. Chips still go everywhere.
One last important observation is that even if you use a router table it will grab the work and pull it out of your hands. The key to this is that you must never try to trim more then a radius of material. In the case of the 1/2 bit, if you try to trim 1/4 or more it will certainly pull away from you. If you use less then the radius of the bit you can slowly and controllably remove metal safely.