I think the question here comes down to defining 'some' leather work. Leather is such a undetermined thing. If you're speaking of thin garment leather then many vintage all-metal machines should suffice. It's when that thin piece of leather becomes four layers or eight, or the leather you're using is much thicker - that's when you can begin to stress any sewing machine. Help us all out here and little and give us an idea of what sort of application. As thick as denim or canvas? Twice that thick? The Singer 28/128 was produced from the 1880's into the 1950's, and there's nothing wrong with that, but you may find slightly newer models more convenient when say... buying bobbins.