i'm more interested about why porsche ever did the different quarter detail in the first place. i realise that they had to redo the quarters anyhow (convertible to coupe) but one wouth think there would be some cost savings to keeping them as similar as possible (for example, it is my understanding that 987 side vents don't fit the cayman and visa versa without modification).
i suspect that withhout the hockey stick the coupe would look a bit 'slab-sided' ie, retro; the hockey stick gives the impression of a flare, or hips, as you move backwards. the 987 doesn't need it as there is no roof to exaggerate the flat sides. the 987 vents look a bit tacked-on to me, however, which is why i've always preferred the 986.
so, a 987 with the hockey stick would have the appearance of a bit more 'back' (cosmo says she's fat, but i'm not down with that) which is always a good thing in my book.