A two-piece suit is ideal for those who want a sporty look, but expect just that little bit more comfort. A leather combination pants + jacket is safer than textile, but has a weak point compared to the one-piece suit: the connecting zipper. Everything is as strong as its weakest link, and that makes two-piece suits suitable for use on public roads rather than on track.
This becomes clear when you look at its composition: a two-piece suit rarely has extra sliders (except on the knees) and the hump is certainly not omnipresent.
Leather always stretches a bit with use. So don't expect your suit to fit you perfectly the first time you put it on. It has to be tight, and consequently it's not recommended you put on many layers underneath. Thermal underwear is best suited.
A leather combi is pre-shaped for extra comfort when sitting on the bike. Not for being comfortable when standing upright or slouching on the couch.
What if it rains?
Leather and rain, two things that don't really combine that well. That doesn't mean you can't keep on riding in bad weather, with a specially designed raincoat.
Leather has specific properties and therefore requires certain maintenance products. Here you can find how to maintain leather motorcycle clothing so that it stays at its best for longest, but it is always advisable to read the manufacturer's guidelines as well.