Who to have Perform PPI

[TripleTrophy]

I am looking at an '01 Boxster S with 135,000 km on it. A two owner car, this guy has had it about 10 years and 115K of the mileage, so it seems to have been used consistently. From the pictures it looks great (and there appears to be a 911 in the background). The IMS has not been done, but he claims to have had it regularly maintained by one of the local Porsche specialists.

The question is do I use the same guy to do the PPI (and likely an oil change/filter cut) since he already knows the guy (and has told him he is a fool to sell it), or go to another specialist out of concerns of bias?

Thanks in advance.