I can only regurgitate the results of a lot research, but aside from limiting the forward/rearward movement during articulation, the term "long arm" needs more refinement.
Most people tend to think of "radius arms" when you mention "long arms". Radius arms do improve articulation, but bind ever as much as the stock short arms. Also, caster changes as the front end compresses/extends, which may be a handling issue on the road; however, Fords used radius, long arms, for years, so don't think the caster issue is much of a problem.
In my opinion, a 3-link long arm, with track-bar, is the best of all worlds. The 3-link eliminates the binding that is present in both a 4-link, and a radius arm set up.