That's indeed a valid consideration and I have no problem with anyone having someone else do the work (most of the work done on our cars is done by other people as I don't have the space/time to do anything but the simple stuff). My point is that you can get the same quality (possibly better) work done at places other than the dealer for much more reasonable rates.
I like futzing with my Cayenne as much as I like driving it. Look me up on 6spd and you'll see a raft of things I've done because I enjoy it. If I have the time and think it's something I can manage, I'll tackle it. If I don't have the time or ability, I'll pay for someone else to take care of it for me.
Which is interesting given that you mention Tysons. Under their old HBL moniker they had a horrible reputation for damaging cars and then denying it. It's only because Rockville pissed me off (by damaging my Cayenne and not doing what I asked them to do) that I've recently started going to them (and so far I've been happy).
I don't remember what they quoted for an OCI, but it was Tysons that wanted $300 for the fuel filter drain.
You could be right, but I have no problem not giving my money to people that don't want it ;)
Then why can Indies charge so much less? Why can other non-Porsche dealers (so they should have similar overhead for the size of the shop, training, personnel, etc..) charge less for the same work? High end car dealers charge what they do because they know may people believe they "must" take it to the dealer and believe there is something special that justifies the higher prices.
Not sure what you are talking about costs or "what they have to go through". I have a PIWIS account myself and you only have to pay for the pages you pull (usually less than $2/page). It's not difficult or costly. Any shop that deals with Porsches regularly has a Durametric which will perform most of the needed diagnostic functions (yes (especially with the 958) the functionality is limited compared to the actual PIWIS and PST units, but it gives everything that is needed for most issues). The Professional Dura is ~$700 and even if a shop wanted to get a real PIWIS they are only about ~$3k (high for DIY, but noting for a shop that does a lot of Porsche work).
And what is that little stamp in a booklet worth? Nothing. It's the actual maintenance records that people care about.
And I know for a fact that my "visual inspection" is more detailed that the dealer's (at least Rockville and Tysons) because they suck the oil out the top and never pull the under trays off for the OCI service.
One argument that I've heard over and over in threads like this is "the dealer will take care of you". Being a 996 owner I know fear and pain around the IMSB. There have been stories of cases where dealers went to bat for the owner and got PCNA to pony up to a new engine even though the warranty had expired. In all those cases it was for people that had bought multiple cars and done all service through that dealer. On the face of it that does sound like a good reason to be loyal to your dealer as new Porsche engines are not cheap, but when you actually do the risk analysis it falls down. The chances of a catastrophic failure on a well maintained (and which includes not being a garage queen that rots on its tires) modern car is pretty slim. Most Porsche dealers are also part of larger chains now and have higher employee turnover than they used to so even though you've given them all the money, you aren't likely to have that really long personal relationship that used to be possible.
If you can't or don't want to do your own service work, there is nothing wrong with that. We all have or own interests, skill sets, and priorities, it's all good. I'm just saying that no one should over pay for anything. Given that you mention Tysons, we are obviously in the same area and there are a few good Porsche specific Indies in our area that charge significantly less than the dealers.
As I said previously, if you really want to take it to the dealer, that's your business and I'm glad it works for you. I just do my part to make sure that people know they really do have an option and there is nothing special about what the dealer does that a good Indy (or yourself if you are so inclined) can do.