i've used both APC and MAS K series, and the APC wins hands down for getting the most out of an engine. I have a MAS Scimitar on my P-51 and it pulls nicely. I stopped using MAS after witnessing too much flex and wobble on my engines, and APC is recommended to use on Saito's which is what I use.

Any prop can cause great harm. Always be careful around them and make damn sure your plane is properly secured when running a motor. One of the guys at my field was running up his plane, which had a DLE 30 and wooden XOAR prop onit. The wings were at the very top of the hold back on the run up bench, and when he throttled up the left wing lifted up and the plane spun around and chopped his arm up big time. Luckily there were other guys at the field who saw it and was able to get the bleeding stopped and get 911. They had to fly him out on a Flight for Life. He lost some use of his right hand and has grooves in his arm from where the prop chopped through.

Does not matter what prop it is, or what it is made of, any prop can slice you up. APC do have a sharp edge, but when balancing, sanding the leading and trailing edges helps reduce the sharpness, but it is never a good idea to finger flip a prop without some sort of protection be it a glove or a chicken stick. I found mechanics gloves with the knuckle pads work great for this.