This is a sequence rather than a machine. Stumps are treated, slash is treated, the soil is tilled, scarified or mounded, and then the site is planted — and each step constrains the next. A site prepared poorly cannot be planted well, and a planting window missed cannot be recovered later in the year.
That window is the governing constraint. Site preparation must be finished before planting, planting must happen in conditions the seedlings will survive, and the client's schedule is set by the season rather than by contractor availability. A machine that is 20% faster but arrives after the window closes has no commercial value at all.
The dominant cost variable is the ground rather than the vegetation. Rock content and stump density determine tooth wear, gearbox loading and achievable hectares per day, and neither is visible from a brochure or reliably described in a tender document. Survey discipline is what separates contractors who hold their quoted cost per hectare from those who do not.