i had the exact dilemma it was either a series 7 or a r33 gtr
i was so close on getting the fd but as soon as i test drove the gtr my mind was set.
the gtr just felt beasty, and had alot more room, as in perfromance wise there are both good but i just love the pull of a gtr.
i think you should at least test drive both cars then you would know what you want.
goodluck!