My power miter saw is in my garage for cutting 2X4s and such, and comes into the house when I am doing baseboard trim or crown molding. It has no place in my woodshop. I do not trust them for small pieces of wood. Many have a large gap in the fence to allow for blade tilt, and really need a secondary, or auxilliary fence, for cutting shorter pieces of wood. I just think their sweetspot is dimensional lumber and trim, and not small pieces.
For routine cutting of ready-made blanks to size, I use a 10" tabletop bandsaw. (I own a heavy duty 14" bandsaw, but rarely use it for pens.) I use the little bandsaw on for wood, acrylics, and Corian. Has sufficient power to do a nice job on items that are up to about 1" thick. Will do thicker material, but tends to be underpowered for bigger items. The biggest downside of a small bandsaw is that they have a small throat on them, but for cutting pen blanks, this is not an issue. For my own blanks, I use my table saw to rip larger boards to the necessary width, and usually crosscut with a radial arm saw, which I've owned for 35 years, and feel comfortable using. In my opinion, it is far safer to use than a power miter saw. Long-term, I am planning to builds a tablesaw sled just for pen blanks, which will give me the flexibility to easily cut precise angles on the blanks.
Obviously, lots of ways to skin this cat ... but please consider alternatives to the power mier saw for cutting small items.