The major problem I have with Akimbo vs the Bone is the Akimbo's bottom attachment. It's a pinch point / friction plate. So when you sit into it, it's pressing on the line, and when unloaded it can move a bit.
My problem was when you release the device to descend, in an effort to make a smooth long descent on a swing or to just a lower point in the tree the device goes, very quickly, from quick descent to almost freefall like fast drop. (
@JMerritt I saw an Akimbo prototype my buddy has with a new attachment point that looks like it resolves this issue. Thing was really cool)
The bone can't really ever go into free drop mode. All this leads to the Akimbo being smoother going up, but I don't like the trade.