i have worked at 2 dealers and the last thing I would do is take an import to be serviced there.. good luck!
re 100,00km service, Gavin will use any parts you ask him to, but by default will give a quote on nissan parts. The service would include timing belt ($120 for nissan item i beleive), GTR water pump (~$200), Oils, Filters, Sump plug washer and maybe gearbox - not sure.
$860 does sound a bit high tho, i thought it was around $700 for that service.
dave