I have the extended warranty to 150,000 miles. It may say bumper to bumper & drivetrain, but it still doesn't cover everything. I had a temperature sensor go out and it wasn't covered - $250 +/-. At 70,178 the guibo - rubber connector between the drive shaft and rear axle - was cracked (lots of threads on this). Even with the extended warranty, it still cost me $100 deductible.
My advice - bank the $1,600 you would spend on the warranty. If you have any repairs pull from that, and most likely you'll still be ahead of the game. Unless your Transit has hidden damage or is a lemon I've found mine to be pretty much trouble free. Regular oil changes at 10,000 miles (mine's a diesel). Rear brakes, temperature sensor and now the guibo; need new tires soon, but otherwise trouble free. That's putting on almost 60,000 miles in a 12 month period.