Sorry fellas, but I'm going to swim against the tide here to a certain extent. Let me first concede that if you're going to be clearing Amazonian jungles all day every day, yes, a dedicated clearing saw is the answer. However, I have found that if you choose the correct blade/line for the job, a Kombi will cope admirably. KM 131 has to be the choice, in case you're going to use 2.7mm line, although it lasts longer than 2.4, it requires more power. For what they cost, I'd recommend having two cutting shafts, one with line, and one with blades, as I think the " universal " guard is being phased out. ( Not sure about that, I do know that they're moving towards single purpose guards ).
I think I have the Autocut 27-2 head for 2.7mm line, and my most used metal blades are Oregon 3 tooth blade for grass/scrub, or for brambles/heavier stuff, The 3 tooth mulching blade ( which requires patience, and a different action for best results ), or the amazing EIA type blade, which will cut wood up to 75mm easily. It's great for clearing hedges that haven't been touched since dinosaurs roamed the earth.