On the average, mono will cast further(low memory mono).
This depends greatly on what line you are using. Line diameter is part of the equasion here too. The larger in diameter of any line, the heavier it gets and it will shorten casting distance.
If your using 10# mono, and switch to 10# power pro, the power pro will cast further because of the tiny diaeter and its light. If you compare 10# mono to super line of similar diameter(30# super line), the mono is likely to perform better. The mono is smoother which also creates less friction-drag on the rod guides.
In the end, mono fished against a super line of similar diameter to that mono, the mono will cast further. If you choose to use a light super line(up to 15#), it will greatly out-perform the mono of the same line strength because of the lack of diameter.
Did that make sense?