I have the 1445 brush cutter. I love it. 4" saplings get mowed. As others have mentioned, if you can push it over, it is mulch, on ridiculous slopes, and yes, you do need to keep people 100+ yards away from it. I mow wearing a chainsaw face mask, just in case. I have only had gravel hit it, but wearing glasses, that was scary enough. I try to mow with a spotter, but that's because my slopes are 20-30 degrees, and I can't always mow down slope. My fear is finding a badger burrow the hard way.
Having used a number of other brush cutters, I have to say that the Power-Trac brush cutter is way safer in my opinion. My opinion is somewhat colored by a run in with a low hanging branch that nearly pushed me off a Ford tractor into the path of its brush cutter. On the Power-Tracs, you sit behind the brush cutter, making it much safer in my opinion. Not only are you protected by the ROPS, but you get to cut the brush before you get to it, instead of after.
Yes, I would prefer a chain guard.
No, I haven't figured out how to mount it.
I'm considering a bar between the two front wheels to help push saplings over. Not high on my to do list.
I probably spend half an hour servicing it every six hours. (Put the mower on some steel sawhorses, sharpen the blades, grease the blade bushings and bolts, and tighten the bolts. With an impact wrench and an electric grinder, it goes very quickly. I do weigh my blades when I'm done sharpening just to make sure that they are balanced along the blade, and with each other.) This is pretty typical for any brush mower; you are always going to be hitting solid objects.
To the original poster's question, personally, I would consider buying the brush cutter and trade my neighbor for mowing services. YMMV...
Flail mowers are safer, but they take a lot of power, and they don't do as well on bigger scrub/trees.
All the best,
Peter