SiL has an Ecosport 1.0 140BHP model, one of the very last ones before they dropped it for the Kuga. It goes like the clappers when your foot is down, when driving normally it is smooth and quite like no diesel could ever be, and gives excellent economy. I actually really like it.
Small engines are less stressed than big ones. A large, heavy piston in an engine spinning at, ssy, 4000 RPM "weighs" hundreds, perhaps thousands of kilos more at the top of its stroke due to inertial forces than a small, light piston ever will, and is therefore actually more likely to lead to a mechanical failure and places more stresses on small ends, big ends and mains. Engines arent like muscles, they can't be stressed or strained - an engine is good until something physically breaks, or it wears beyond its operational tolerances, and a small engine is a lot less likely to suffer the former and no more likely to suffer the latter.
The early Ecoboost problem wasn't directly engine related. A steel coolant pipe outside of the engine was prone to corrode very quickly, and once it had rusted sufficiently all the cooant would drain away. Obviously, without coolant an engine doesnt live long, but it wasn't an engine problem per se and was fixed on later cars. If you buy an older version just clean up the pupe and paint it with hammerite.