No, I would never buy the same car two times in a row, regardless of the engine (ok, M6 doesn't count ) That's just boring. I need a whole different model line.

But, if I had to choose now between a 645d and 650i, I would still take the 650i. I like driving gasoline much more, since I like to rev up the engine and such. You can play much more with that engine.

However, 700 Nm of torque (or was is 800, let me check) is something not to diss with

Max. output 329.5 PS (325.0 bhp) (242.4 kW)
@3800 rpm
Max. torque 700.0 Nm (516 lbft) (71.4 kgm)
@1900 rpm