Anyone use quantum FX? It's sort of a modular thing, but just for effects. It's ultimately a subset of what Reaktor can do, but just a little different from synthedit or synthmaker since those give more granular access while Quantum FX comes in bigger chunks. The interface looks horrible and acts horrible, but that's sort of similar to synthedit.
It's an older product, so I'm not sure how it holds ground in today's context, but it looks like an interesting package to throw together custom effects.