Hey guys, I like/love using fully defined "black" splines. Here's an example:

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I like splines for two reasons:

1. They are aesthetically pleasing.
2. They can be constrained to have curvature continuity, unlike circular arcs that can only be constrained to have tangency continuity.

In a way these two characteristics are linked together by nature. There is only one thing in nature that is (almost) perfectly round - your eyeball/lens. Apart from the stalks of some plants practically all other curved objects in nature have curvature continuity - that's what makes them aesthetically pleasing.
This is true in engineering as well - you do not want to have your airfoil made up of a series of tangential circular arcs - it will be inefficient and have terrible stall characteristics.

Incidentally, the tail-wheel fork (spline version) shown would be somewhat lighter because it has strength where needed and less material elsewhere. (IMHO it looks nicer too!)