The OmniBlocks really shine when you use redirects on the rigging line. When every pulley in the system between the friction brake and the primary block swivel to self-align, the rope isn't dragging (under load) across the side plates of multiple devices, and rope wear is reduced. Friction is less, which matters if you need to lift the piece a little or keep tension applied. It all just runs smoother, and you can tell it... the noise level of rope-on-metal is lower.
I usually am using my wife for the groundie, and I don't want her in the landing zone, so I redirect the line so that she doesn't need to enter it until the piece is on the ground. Since switching to the OmniBlocks, we can set up for this pretty quickly (the pulleys are all midline attachable) and I can keep the riggling line redirected so that it can't interact with the load, as it can when it goes straight up to the block and the load is swinging. It only takes a little bit of tension to pre-align the redirect pulleys and pull them out from against the tree, where you can get a quick visual of the whole setup and spot any issues (such as a branch that dropped across the line somewhere, a stub that might be an issue, etc.) which I rather like. I can also immediately see if the redirect above the friction brake needs to be reset, as this one can sometimes twist around the trunk to where the feed into the brake isn't good. Little stuff that I found just makes them nice to work with.
There certainly isn't anything they do that is required... lots of ways of getting the rigging done, they're just nice to use because of their feature set. Negative blocking, I always switch the primary out for an impact block. Otherwise, I use the 2.6" OmniBlock, and the 2.0" ones for the redirects.
They are extremely useful for other, non-tree stuff, as well. I think this new, big one is being marketed primarily as a lifting block in non-arbor industries.
