I have one of the generic M328 units and it performs quite well against my professional grade equipment, in the use cases you specify.
It can get caught out on classifying some types of transistor (UJT/PUJT for example) and thyristors, and yes it'll show zeners as two diodes in reverse parallel (if the zener voltage is low enough, ~5V iirc), but for the cost it's a very capable little gizmo.