possible to drive displacement with vertex colours?

[wizzackr]

Hi, quick question: We have separate objects that share identical edges and want to displace some of those aligned objects. Now, assigning different shaders obviously blows the edges apart as one surface is displaced and one is not, so the question is: can we somehow use vertex colours to drive the displacement towards the edges to zero? We can render them using VRayUserColour, but those do not correctly show as displacement and mutiplyiong the displacement map with them does not correctly show. Any idea?
Best,
J