unrolled cores are not necessarily crappy cores.
Agree however they can't be compared directly. It takes 80 clock cycles for a Bitfury rolled core to complete a hash where as an unrolled core will complete a hash in one clock cycle. So clock for clock Bitfury 756 rolled cores complete about the same number of hashes are 9 unrolled cores. This isn't to say one method is better than another. They are just different. Given similar die efficiency a 9 unrolled core chip and a 756 rolled core chip would be comparable size, power usage, and hashpower.
Another way to look at it is GN's 768 nonces per clock cycle would be the equivalent of Bitfury announcing they have a new processor with 61,440 rolled cores.
Any way you slice it a single GN processor is a staggering number of cores each one processing a full nonce every clock cycle. No existing design comes close to putting as much hashpower in a small package (Cointerra probably will be similar but so far specs are unknown).
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And much of that can be expressed as a GH's / Die area, that would give you a measure of efficiency - or in its simplest terms, GH's/S. per square mm of die area - at least when comparing like for like (all 28nm's for instance)
Agreed and by that metric the GN is extremely dense. A huge amount of hashing power per mm2.