Pfaff sewing machines are the best in the business, outside of Adler. Why do I say that? Adler machines have 1/2" main shafts, and all other machines have 3/8" main shafts (both German machines,..... imagine my shock) But,....... any true industrial sewing machine in the hands of a professional upholsterer, and not used at full speed 24 hours a day in an industrial setting, will last forever. These machines were made to sew 3000 stitches a minute 24 hours a
day. The Consew 226- R that I use for almost all my sewing is over 40 years old. The next 5 generations of my family will still be using this machine, and it will perform flawlessly, with only reasonable basic maintenance. There is nothing the average part time, or full time for that matter, upholsterer can do to screw up any industrial sewing machine.
The point is that if you're only sewing one or two interiors, or less than that, you can invest in any good industrial machine and sell it for almost what you paid for it, or make a profit. Maybe not in this economy, but definitely in the long run.
No one lives forever, the trick is creating something that will.