[noelwelsh]

Clarity comes from familiarity. It's not an objective measure.

The speed benefit is well known, as is the corollary, premature optimisation. I expect checking for null is even faster if speed is the main concern. It's an engineering tradeoff, just like making the abstraction to a monad (or monad plus). In the normal course of events I'm more concerned about flexibility than performance and would prefer the abstraction.