"Where the [Suhr] Koji is a ‘feed-back’ design, the Woodshed is a ‘feed-forward’ design. ‘Feed-forward’ works by the signal going into the side-chain, which controls the gain-reduction of the whole thing."
Merlin Blencowe's Engineer's Thumb is a feed-forward design, but this is not a variant of Merlin's ET, 'cause the ET is an OTA-based comp, like the ubiquitous Dyna/Ross variants — so at least it isn't that.