Since I bought my Woodmaxx flail mower I have not used a rotary bush hog again. I think I've owned my flail for 5 years. I should sell my 6 foot rotary brush hog.....just never get to it. I have a 78" hydraulic side shift model and a 38 HP tractor. Get a flail mower wide enough to cover your wheel tracks for sure. After that.....the width will primarily determine your ground speed with a flail.....IMO.
Lots of the more popular brands of flail mowers are made in Europe and some get a little pricey. Not sure why Europe evolved toward making so many flail mowers...but they do.
A Woodmaxx is generally thought to be a decent quality imported (asian made) model by most that own them. There are many other good brands too....it depends somewhat on your want/need/afford for quality. I bought mine primarily based on what I read on Tractor By Net.....which I have used extensively when buying 'chinery. Lots of good reviews by owners over on that site ....last I looked. Check their site.....sometimes they sell out of the models you may want, and you may have to wait a while......so I would order early. They do offer "free" delivery. I read that Titan was now offering a flail too....but heard some bad reports on that brand. I dunno more on that brand of a flail......sometimes asian based stuff can be sketchy......but Woodmaxx is comparable to American based quality.....and I have been quite well satisfied with my model.
One thing that is a bit irksome to me......is that when shifting to the side....the mower weight causes the right side to become lower than the left side. I need to re-adjust my 3 point linkage in that situation.....and I do wish I had a hydraulic side link for that reason. I do have a hydraulic top link and that is helpful to quickly level the mower after changing implements.....but that does not change like the side shift does. Normally I get along pretty well by somewhat compromising my set up between centering the mower and the side shifted mower. I'm too cheap to buy a hydraulic set up for the tilt changes.....as it would require another valve as well as a tilt cylinder and hoses. If I did more mowing in a yard and such I would want the tilt cylinder.
I think you can do the trail you show quite nicely. I have chewed through some pretty heavy cover with mine and the biggest limitation is heavy, thick grasses. It takes some time to mulch that heavy grass.......so I go slowly in that situation. By comparison, Leafy / woody stuff (like in your pic) is pretty easy to go through.
