The Performance does not run a quarter mile in 11 seconds flat. Lowest times have been 11.3, but average tends to be around 11.4/11.5. Also the lowest 0-60 times recorded is like a 2.98 and that's with 1' rollout.
Warranty is only partially an issue for me, lack of supercharging is the other, and then like Knight said - having to drive across the country to one little shop to get an update. Not that I'd feel like they're really all that necessary at this point since I'm not on FSD and probably never will be unless the price is much more within reach. Though they do add nice features once in a while.
If I were to even do this, I'd probably want to just go straight to stage 3 - as long as it's proven within safe limits of the hardware and reasonable price, which is another conversation.