Does population "render quality" has any tangible effect on the amount of RAM being used (or object's actual visual appeal thereof) in a project?
Render Quality has no effect when Ray Trace Objects is enabled, which it almost always should be since it gives faster render time *and* higher quality. The only time you don't want to ray trace objects is if you need displacement on them, and in that case it should be done on a per-object basis ("Force Displacement"). I think it would be ideal to "hide" this "quality" setting at this point as it is very seldom useful/needed.
That being said, when Ray Trace Objects is disabled or Force Displacement is enabled, then higher object render quality settings will increase render time, RAM use, *and* quality.