To be clear, I am still very happy with my Tesla. The car is amazing with only a few bugs that I am confident service will fix. I "sell" the Model S, the X, Elon Musk's brilliance, and his companies to many people, just not the Signature. I don't mention that my car is a Sig, that's not important to me. When a very interested buyer asks me about a Sig X, I tell them to go regular production. My reason for the Signature initially was to get the car early, not for any other reason. The premium for early was worth it because when I upgraded from a fairly low P in the 1400's I was told July instead of early 2013. This turned out to be more than 5 months off for my Sig, and it would have been possible to get P1407 in December (literally the same month). When I finalized in July, I was told October. When my Sig didn't deliver until December after multiple missed windows and radio silence from Tesla, it was delivered after a number of regular production cars (Performance and non-performance). The only reason I think I made December was because I threatened to cancel. To get the car delivered when I did, I had to take a day off, rent a one-way car, ride a bus, and then wait around in a small town 179 miles from my home in the cold until it showed up by trailer. Otherwise, it would have been weeks to months later according to my DS.
I have repeatedly asked Tesla over the phone and in emails for a simple apology, an explanation, and/or both. I still wouldn't recommend a Sig for the reasons posted here, but it would provide me some closure on this. For some reason, they aren't interested simply saying "sorry about the missed windows and the later than intended delivery."
Why wouldn't I recommend Signature? You get nothing extra and you don't even necessarily get an early car. Since you can now get a Performance car in 1-2 months off the line, there is no reason to not be minimally patient and get a more-refined car at a lower price.