This Lanparte Side Grip 2 from CoollCd (in China, I think), has a lot of flexibility and range of movement.
On real advantage I see if that they don't slide on, but can be attached from the bottom, right in between my O-Box and O-Focus. And, they can be angled outward or positioned in any number of ways. And they look 'cool'!!
Then again, there's the Shape Quick Handle Rod Bloc:
which slides on, and can only be tilted up/down (but not side to side like the CoollCD
I have a Zacuto Studio Baseplate
and am considering the Shape Composite Shoulder pad
which looks very comfortable, but would make the camera's center of gravity higher than a shoulder pad like this from Zacuto
So, my main concern about the arms is whether they would be too long to use for some reason, or if I'm missing something basic that makes my possible choices unacceptable.
As for the shoulder pads, I've never used a rig before, so ... I don't have the experience to even guess what makes one more attractive than the other - so ... I'd appreciate any and all comments.