Well, once again, simple common sense dictates that if dealers make lots of money from these warranties, then most customers never recoup their investment. Period. There is no way around that.
Now, with interest over 5 years, that $1700 will end up costing closer to $2000, and you only gain 2 years of warranty on the powertrain. There is probably (I'm guessing here, but it makes statistical sense) a 80-90% chance that you will not recover your investment. In other words, there is an 80-90% chance that you wil LOSE $2000, and a 10-20% chance that you will actually recoup some of your money and even less of a chance that you will save money...
When I was a student, I worked as a TV & Stereo saleman, and I absolutely loved those extended warranties. I made 40-50% comission on the warranty, which was often more than I made on the equipment, and 99% of people never benefitted from it. Recently, I went with a friend to a major electronics chain that would match any advertised price plus 10% of the difference. They happily discounted on the heavily discounted price he got somewhere else, but then they worked on him for 30 minutes trying to sell him the warranty (they were desperate to salvage their profit margin). They tried to make him feel stupid and guilty by not taking it. Good thing I was there to keep him from caving in.
Salesmen are pushy with extended warranties, and I know why, so I never ever buy them. So far I have never regretted it. They are a scam! Sure, you might get unlucky some of the times, but you'll still be ahead of the game.
Some of the comments here are making me think though. If I can really expect a high probability of needing a new tranny on a 5-7 year old Subaru, then perhaps it is not the car for me. I find that totally unacceptable. I have never changed a tranny in my life.