My comment was related to the "worth/value" of signing up to the classic register - specifically the immediate benefit I received by doing it, I was going to have the car serviced at the OPC with or without Classic Status.
Also - although it does not appear to be a policy in force across the OPC's - they have been giving me 15% off parts over the counter - not just when fitted by them - without me asking, again, all it cost me was a phone call and 2 emails.
As to the "what did it cost compared to ..... " - here's my take on that. Others have different views, experiences, requirements and expectations... so this is "me"
There are a number of variables in play here
1) Good and independant (certainly locally to me) don't always go hand in hand. My nearest GOOD independant just sold up to someone I would call a "special"ist - I don't trust them. - when they say things like "oh that needs a computer so that's a bit more labour....., and then pull out chinese clone of a PIWIS 2 and say - "Porsche gave us that because we do some work for them" .....
The next nearest trusted one on previous occasions have been approx 10% cheaper than OPC for individual jobs. One other, quoted about 15% more for a couple of jobs.
2) Car is under porsche extended warranty and therefore I have factored in having an OPC servicing.
3) 12 year service included both sets of fluids for the PDK, oil/filter, air filter, belt, plugs, brake fluid - I was quoted just around £1300 - I paid around just about £1000 in the end, if I take the menu pricing from some of the well respected independents I think that is comparable for the work done - probably (guessing) £150 maybe £200 in it (if I was lucky). The OPC also picked up leaking front coolant pipes, which were covered by (and fixed under) warranty.
4) I am freelance, if I don't work, I don't get paid - nearest trusted indy is an hour + away - in the middle of nowhere - so it's effectively a day off - OPC collected and delivered the car to me.
For me, aside from the Warranty requirement which won't be for ever, it's about the hands on the tools, not the name on the door, to date I have found no issue with the approach or work done by the OPC - its not cheap - but it fitted my requirements. I need some work done soon on exhaust fittings - will be using a (trusted) indy for that since even factoring in taking a day off I a still quids in vs OPC - so its not always the right answer but when it is 15% off the cost is icing on the cake.