Horizontalism vs verticalism

On the left, a long standing problem is: how do you go about Political organisation. With very broadly speaking a historical split between horizontalism (being a more distributed anarchist approach) and verticalism (being a more communist approach with a strong party form).

I first came across the sniping between camps in Inventing the Future I think. They lay into "folk politics", their name for horizontalism. Kevin Carson gives a lengthy rebuttal of their critique.

See critiques of horizontalism and critiques of verticalism, but I am most interested in the synthesis of horizontalism and verticalism.