The question is:
how long are you intending to keep the van ? The older the van the less the issue becomes an point of contention.
would paper copies (not VW main dealer) allay any fears a prospective buyer had regarding correct servicing regimen had been carried out (In the future).
VW factory warranty! it will give VW every excuse to wriggle out of any future warranty claim?
Our system says your van has not been serviced in line with VW recommend standards sir ! (prove it)
I suspect the Non VW service may be an issue for many in the first five years.
I have my own thoughts regarding VW servicing, which does not necessarily support the above, but people are naturally risk adverse when it comes to trusting that anyone other than a main dealer can do a proper service (particularly for the first few years)
only you can decide what’s right for you i‘m afraid