I think my 1070 is a good machine. I bought it for a good price and it probably wasn't taken that good of care of but I have done a few small things to it and it is pretty reliable. Most issues I have had have been electrical- bad connections at some of the plugs. Some I still haven't addressed completely, the fuel and temp gauges work when they feel like it, again bad connectors. It seems pretty bullet proof mechanically.
My only complaint is that while it has plenty of power, it has real wide turfs and is 2wd so is not a real great puller. Not the tractor's fault and this will hopefully be solved if/when I switch to loaded r-1's. With the wide tires also, I need to get wider attachments than is practical to cover the tracks. I am about 78" wide so really would need a 7' box blade, but with those tires I don't think I could pull it well. When I switch to the r-1's I will be right under or at 6'. This is one reason I would have reservations about an 870 or 970 is that they are physically the same saize but with less power, I wonder if that would make to low of a power:weight ratio. I bush hog with a 6' mower and don't think I would do it with much less power, however a smaller mower would be too small for this machine I think.