I'm no operator, but the 863 is a good digging machine.
Don't be fooled into thinking that because a machine has only one tilt cylinder, it is weaker than a machine with two. It all depends on the pump, volume of the cylinder and area of the piston or pistons.
The single tilt cylinder on an 863 is BIG compared to the twin cylinders on an 873. The advantage of two tilt cylinders is to make it easier to get in and out of the cab, without that big single cylinder tower on the cross-beam.
The 863 won't load high like a vertical-lift machine. If you're going to keep low most of the time, the 863 is good. Go for it.