I'm sorry. I didn't understand why you wanted the machines you talked about. I thought you were just starting out in the business and were looking for advice on what machines to get.
I'm originally from Waukesha. We moved to Whitewater, WI when I was about 4. I now live in Lake Tomahawk, WI and yes, I do have my own upholstery shop. I am far from an expert on sewing machines, and even farther from being a legend, but I can answer most of the questions that show up here, and I have worked in a number of different factories, so I know some of the machines available. Basically, you can get the supplier of the machines to make you any kind of machine you want. Zippers, for example, were sewn with a machine that had 4 needles and two folders. All you had to do was feed the fabric into both sides of the folders at once, and the machine sewed the fabric to the zipper chain with two lines of stitching on either side of the zipper chain. That machine did nothing but that for it's entire life.
What you have to understand is that if you go to a factory that does sewing, you will find dozens of machines dedicated to only one operation. The concept of a multi use machine is no help in a factory setting. It is much easier to take the work to one dedicated machine than it is to adjust the machine to do different jobs every day. Most sewing operations are very straightforward and don't need specialty machines. Other operations, like making button holes, or doing French seams, require dedicated machines.
What kind of leather and what kind of sewing operations are you talking about? If you're talking about leather that is used in seat covers, there would be no problem. Even if you're talking about really heavy leather, there are machines that will handle it. I have a machine that will sew through 3/4" of leather, and could do more if not limited by the lift of the foot. There are machines that can sew much heavier things than that.
No one lives forever, the trick is creating something that will.