I am sure Crab didn't mean it, but I am afraid that some will misunderstand his post of saying that the actual conditions when given a Special VFR clearance are neccessarily worse than the VFR limits for helicopters operating outside of a control zone (CTR). Or to rephrase, that once exited the control zone in which you were operating under SVFR, in order to continue under VFR the visibility needs to have improved, else you can't proceed.
No, the SVFR clearance is an ATC permission, in this case to cross class B airspace when VFR isn't available (in some US airports I believe) or the weather precludes VFR (again I don't fly in the US but I believe when the ceiling is below 1000'agl). Helicopters can fly SVFR in class B with visibility less than the Class G VFR limit of 1 statute mile. Therefore on exiting Class B SVFR into Class G VFR you could be going from worse visibility limits to higher ones.
So, while he was in Class B - IF the visibility was poor, he would have to have an improvement in vis to 1SM as he crossed B to G in order to claim VFR.
It could well be that he had more than 1 SM all the way through B and out into G but he seemed hesitant to confirm VFR when asked which could have been visibility related or cloud related.
We are pretty sure that soon afterwards he entered cloud (definitely not VFR) where it all went wrong.