In my opinion dollars do not come into play as the deciding factor between those two. They are very different vehicles as far as the driving experience they provide. If you want the sportiest possible then go for the X5M knowing that many feel the ride is too harsh for daily driving duties. If you want some sportiness, quickness but a ride that is more appropriate for all duties/conditions then the M60i may be the choice.
I would suggest driving both and see which one feels best for you. If it is the X5M then make sure you are comfortable buying used. If you are then go for it. If not then go for the M60i.
Then again, all these vehicles will suffer from depreciation so maybe don't let that shy you away from a new X5M.
