I didn't read everything written in this thread, but I work exclusively with chrome tanned leather so here are my thoughts.
First of all, the make/quality of the machine is definitely going to make a difference in regards to accuracy and ease of use. The problem with most of the cheaply made skivers is that the blade and the feedwheel run on one motor, so if you want the blade to turn fast (which it needs to in order to cut), the feed roll also must move fast. In this case, you sacrifice control.
On the higher end machines (Fortuna, FAV, etc.) the blade and the feed roll run on separate motors, so it is possible to slow the feed roll down to a crawl while the blade spins fast, allowing you maximum control while skiving.
Having said that, it is still certainly possible to get good results with a less expensive skiver, however the machine has to be well adjusted and the blade needs to be very sharp.
Myself, I sharpen the blade every single time I use my machine.
One thing you're going to want to remember is that when you sharpen your blade, you want to bring the knife to the exact same place every time. I have found that an optimal place for sharpening to bring your knife is 1cm from the leading edge. That means you're going to move your knife almost as far to the left as possible, so that there is only 1cm from the left edge of the machine. I imagine you may have screwed up your knife quite a bit, so it may take a while of sharpening at this position to rectify it. Every time you sharpen after that you're going to want to make sure you bring the knife to the same place.
Having been through this a year ago, if you are wanting to split leather (as opposed to skive) you cannot use a cheaper machine.
For my work I need to split, and having wasted more than a few skins, if you want to use the machine to split, you're going to need a higher end brand with separate motors for the feed roll and knife and which is presumably also more precise and well balanced to start.
Hope that helps