In my humble opinion, and as someone who has paid his £3.5 k and will wait patiently until my Black Edition with SatNav arrives, the V-Spec will be a different kettle of fish.
Think F430 and F430 Scuderia or 911 GT3 and 911 GT3 RS, to the non-enthusiast quite similar but actually can appeal to two different groups of drivers. I believe the V-Spec GT-R will be far more hardcore, of course more power and less weight and maybe no rear seats and a half rollcage as in the RS.
Nissan are not shooting themselves in the foot with this model. it will not arrive here for probably two years after the GT-R and will sell to current GT-R owners as an upgrade and also to a new group of buyers.
Look out 911 GT2 - Nissan is after you as well ......