I have a Techsew 5100. I’m a novice leather worker. This heavy duty machine has worked flawlessly for me using heavy to light set ups. I’ve run #19 needles and #92 (?) thread on leather, rubber and marine vinyl with good results. The heavy stuff? Not a problem, I’ve sewn 0.80” plastic an it didn’t even register as tough.
Likely more machine than most leather workers would ever need unless you’re making sheaths, holsters, saddles and protective equipment. Download the manual and parts list, be curious about how it works and try to get it optimized every chance you get. That’s how to climb up the learning curve in my opinion.