IB is just SB with some new toys and tricks... I thought Haswell was far more of a redesign/tweak than SB>IB was...
Haswell will have a 2011 type chip/socket as well without a IGPU just like SB does/did.
SB had something like a 17% lead per clock per core over 32nm Westmere, with better power to performance and improved clock speeds.
Compared to core2 it seems reasonable to assume generally the same thing will take place as has been taking place since core2, that is 15-20% IPC increases, better power to performance ratios, and generally new instruction sets that will further increase it's performance potential in real world applications.
It has been reported that Nehalem has a focus on performance, thus the increased core size.[4] Compared to Penryn, Nehalem has:
10-25% more single-threaded performance / 20-100% more multithreaded performance at the same power level
30% lower power usage for the same performance
Nehalem provides a 15–20% clock-for-clock increase in performance per core(average)
AVX2 which is basically AVX for Integer work loads should improve performance over SSE, or at least I would think... AVX was a bust for most of us since FP isn't very common, nor is it typically the limiting factor in performance. Of course that's the same forward thinking Bulldozer incorporated, however just like bulldozer the new instructions won't mean anything for legacy and even current/future software until it's coded.