The extended edition is definitely worth picking up, for both the film and the incredible Appendices discs. The Appendices are even numbered 7 and 8 to dovetail with the extras in the LotR set. Well over 8 hours of behind the scenes entertainment there alone.
I did see Bolg, all armoured up and nasty weapon swinging in the Moria sequence. He's in the background though and you will literally miss him if you blink. I meant to check the time code, so I'll go back and do that and post it.
It seems as though a lot of changes were made 'on the fly' this time round. They had the advantage of not having the cost of film processing, as the RED 3D cameras use digital storage media. Therefore reshoots only meant a cost of hours, not material.
The goblins underwent some substantial changes due to the actors overheating in the silicon suits in the smaller sets with lots of light. I shuddered at the sight of one of the guys pouring sweat out of his silicon goblin foot at the end of a shot. They dropped the masks in favour of CGI-ing their heads over the actors in post. This could explain some of the inconsistencies I felt existed in their design, although that is probably down to PJ revising the Guillermo del Toro approved designs after he took over as director.
Given the tremendous advances in mo-cap, principal actors performances are captured down to the most minute detail. The tear that Gollum sheds at the loss of his precious was shed in the same frame by Andy Serkis. It seems strange that Azog stands out as a less completely realised CGI character, unless the revisions were done very late in post and lacked the time to finesse the details more effectively.
Based on looks alone, Bolg would have been a far more dramatic nemesis for the company. He does look a bit more Uruk in stature, so the thought of an überOrc like Azog as he appears kind of makes sense. Less panel beating, more brain cells...