I am using markerCLusterer V3 on a db file from Filemaker to generate a (semi-live) map of current delivery locations, based off of addresses. Grabbing the lat/long from Go
I came across this post because I was looking for the exact same thing, but lucky for me I have made it work!
I honestly didn't do anything special, I followed the integration guide for MarkerClusterer, and then followed the integration guide for OverlappingMarkerSpiderfier and they work flawlessly together.
When I click/zoom in on a cluster of properties that are all at the same address, initially it just shows the "top" marker, but when I click it, they Spiderfy just like you'd want them too!
What specific result are you getting when you try to use the two scripts together?