The main point to remember is that warranties are sold to make a profit. They don't push them on you for the good of their health.
If you have the cash flow to handle the unexpected occasional $1,500 repair then I would skip the CPO. I would definitely skip CPO if you work on your own car for minor maintenance items like brakes and oil changes.
That said, a few people on the board have cars that required several big $ repairs and the CPO really paid for itself. I still feel this is the exception.
My '06 650i has had zero issues over the last 2.5 years other than normal wear items. Car has about 68K miles (110K km) on it. I drive the crap out of my cars (I also track the 650i occasionally) and have used it for several very long road trips to mountain roads where I thoroughly flogged the car.
Straight lines are for fast cars...turns are for fast drivers
'04 M3 - track
'06 650i Cab - daily driver
'02 Highlander - kid hauler
'01 330Ci - winter beater