I don't know what kind of area you have to mow, but I use a 9hp two wheel tractor with a front mounted flail mower.
This is the tractor;
http://www.lampacrescia.com/eng/catalog ... ?id=2&k=36To see the mower, scroll through the implement section.
The handlebars and controls are rotated 180 deg and the mower goes on the PTO.
This will tackle 2 foot high bracken easily, but it is hard work, a bit like steering a 9hp determined pig. Half an acre of bracken would take about 2 hours. It tackles anything I've put in front of it including: nettles, thistles, grass and reeds. You just have to use the correct speed, everything is reduced to a fine mulch. I've had it for around five yers and all I've had to replace are the flail bearings, my fault, I got too close to a pond and must have washed the grease out of them.
I also have a ride on meadow type topper
http://www.youtube.com/watch?v=rr4aJ1zI9_IThis is amazing, it will smash its way through chest height nettles and thistles with ease, but mine is rubbish on grass, could be the blades need sharpening as I bought it secondhand. Takes me about 6 hours to do 2 acres and it isn't hard work, just a bit boring. Haven't tried it on bracken yet.
Not sure about the claims about bracken spores, but to be safe, I've only ever done it before the spores appear.
I transport them around using a ten foot box trailer with a ramp.
Dave