I will be getting a new mini exc. I have been renting an exc 2-3 times per year for a while and am ready to buy. My main projects are ditches, digging trenches for water lines and drainage (in pasture for cattle). I also cut firewood. I usually have polewood delivered and plan to have a hyd thumb on either machine. I dont want to spend the extra money if I would never notice the difference but dont want to regret it in the future. Is there anything I want to do that the 91 would be too big for? Could I pick up a 20 foot oak log to cut with the 71? I had initially looked at the u15 but boy did it seem small for what I want to do.