Wait! You are less concerned about a BMW 5 series reliability in 8-10 years?!? Is this your first BMW?
First BMW - yes. I've had it for 7 years, luckily I researched a bit and got an excellent extended warranty which provides bumper to bumper (including inside electronics) coverage till 2022. The car has been mostly trouble free till the 70K mile mark, so far. Water pump and some leaks were repaired under the warranty.