I have a pretty nice self-powered trailing rotary cutter (I think that may be a mulcher in your area), and a really nice 2012 Honda Foreman 500 ATV. As long as you are maintaining clearings, it works well enough to keep stuff knocked down. If you were trying to clear an area of tall grass and tiny saplings, it would not do as nice of a job. Maintaining a slow steady crawl is much more difficult, especially on uneven terrain. If it is much of a hill, it isn't a good idea at all, the cutter is pretty heavy and the ATV simply doesn't weigh enough to keep good traction in many scenarios. I also have a 2006 Yamaha Rhino side by side UTV that does okay for weight with about 200# in the bed, but at 450cc lacks for power on hills. It has low range which is nice for taking down taller stuff at a steady slow speed, something the Foreman 500 fails at. Where a tractor really excels is visibility in the tall stuff. With an ATV you are waist deep in it and totally surrounded with no visibility. With a UTV you are surrounded by cab and looking over a hood, again with no visibility, but at least you're not getting poison ivy and cut to ribbons by thorns. With a tractor you can look down and see what your tires are doing and set up above all the nasty stuff.
As for the cultivator or seeder, I don't really know. Tasks like this might be better.
For transporting, yea, it lightens the requirements a lot...