hi im not going to get into this but i do upholstry work n chap work n whatever else work. im still in the stone ages n i use an ols ANKER upholstry machine n i use that one for 30 yrs on just about everything. i use it for zipper replacement in coats, i make rodeo chaps n its goes threw 4 thickness of 4oz leather etc.. I also use a singer 111-153w which is a walking foot n that i put wear leathers on one inch thick wool blankets n it goes threw the 8-9 oz wear leather also. so ive use a very new machine n i have broke that one nothing to major but was an odd break. most all my machines are pre 1940s. not saying the new cowboys or techsew or cobras or whatever will not work for ya. but im an ol time machine operater. n i put a lot of hours on machines n if i spend more time fixing than working im not happy. and the other part is im cheap these machines i bought under 400.00 each. they are both industrial upholstry machines. n they go threw leather just fine. just go places n look at machines and take the thicknesses of leather your sewing threw and try them out. that is my suggestion. im not going to say one machines is any better than another. search ebay, craigslist, industrial sewing places, upholstry shops, shoe shops, n check them out they can let ya try theres out or tell you where to look. hope this helps some. Bronc