That is similar to the Stihl Machine we use too. Ours is a combi system, you can swap out the implements. Swap out the brush cutter for the chain saw (and I agree, you don't want to use a chainsaw, you want to use the brush cutter), I can't imagine what bending over running a chainsaw would do to your back.
Stihl makes these combi systems in a consumer grade and a pro grade. We had to replace the consumer grade model medium sized motor- which worked for many many years a couple of years ago and moved up to the pro model. I LIKE Stihl, because if they break you can get parts, or like we do we take it into a shop. If you buy an off brand there is no fixing them, only throwing them away. I would not buy the lowest model in the consumer end, but I would think that the medium model or high model of the consumer end would work just fine for your needs.
My husband will no longer use the regular chainsaw as he cut his hand pretty bad with it, he worked (when I told him not to!) when he was feeling sick and then had the hand accident, which he recovered alright from. But since that accident he is afraid of the chainsaw, the only one he uses is the chainsaw from the Stihl Combi System. Using the chainsaw on the Stihl Combi system keeps the saw far away from you. Of course it is not as powerful as the regualr pro model Stihl Chainsaw but most of what we need, over 90% is handled by the Chainsaw on the combi system.
We bought but never used the hedge trimmer attachment. We could have bought the straight up brush cutter which is shown in your pic but actually the Stihl Combi system is more lightweight and if you use it a lot you appreciate having the lighter weight. We get plenty, plenty of power out of it. Best of luck with your project.