I’ve had similar experiences when moving manufacturing and assembling from one facility to another. Quality will always call for a complete validation for all aspects of the process moving. While you can and successfully argue with and rationalize certain aspects of a complete revalidation, I believe it is always worth mitigating risk and going forth with validation. Rationales can very much so take off much needed time from a relocation project, but in the grand scheme of things the cons outweigh the pros for me personally.
-Tarek