One thing about maintainability of the Black Max prop. The hubs wear in dirty conditions. McCauley has similar hub designs on their new props. It is not a grease hub like the Hartzel. My experience with Caravans is the composite prop, in the worst conditions can get beat up and repaired. They always make overhaul. The only blade I have ever had condemn was from a fire. Conversely with the McCauley prop, same installation on Caravans, the blades condemn, due to edge wear limits (very small damage repair criteria) and the hub condemns due to fretting corrosion. I'm not talking one or two here, I have several Caravans I lease out and it is a trend.
I don't have any personal experience with the MT, but several of our customers have them (I own a repair station as well) and they rave about them. The damage repair criteria is quite generous. On Hartzel composite props, you can have gashes down to the foam. Just mix up some Hysol and micro balloons (little glass bubbles to lighten the epoxy). Let set, sand and paint. If you have issues with the leading edge, which can be cracking or delimitation, it can be replaced by the prop shop. You can actually have cracks in many places, except the lower inch or so. You can't replace the leading edge on a metal prop, one good rock ding and it can be a replacement. Hartzel has more meat to remove on their prop than McCauley usually does. You can ask the prop shop for repair limits on the actual props you are looking at to judge for yourself. The amounts can be surprising.
So if I was working out in the bush with the plane and prop erosion was an issue, I would lean toward a composite prop, or a prop with a grease hub. The McCauley prop is better suited to a paved runway environment, even though it may be a better performing prop. Personally, when I get around to doing the prop on my 185, it will change to either the Hartzel Scimitar or the MT, I get good discounts on both, I just want to fly each before I buy. Sometimes, the performance can be wasted by your individual needs and flying style. Since it may not benefit the flight envelope you favor.