I agree with oosik; the straighter (or more level) the shaft. the less strain on the U-joints. I also agree with s219 that "on the ground" is more stable and puts less strain on the 3 point hitch. When I used a borrowed Wally BX42 that had a low input shaft height so that the angle from my PTO was excessive, I used steel strapping to band a couple of short timbers (6x8's I think) to the skids. That worked fine except that everything I put in the hopper had to be lifted the extra height. The Salsco 6"
chipper I ended up buying had a much larger flywheel that gave a better PTO shaft angle. The Salsco also had a lower hopper bottom lip height than the comparable Wally. I suppose the trade-off is how well gravity feeds on the different slopes of the chutes, but I find a 5/16" gap and sharp blades feed as aggressively as I want.
The price you reported should go a long way to quiet any small dissatisfactions you have with your Wally.