Finally done with this Doohickey. The final version for my Tree farm using the Crossroads mod.
After recently discovering the power of "Beams", i got straight to work, modifying the farm in a way that the saping is hit with a green "Potential" beam, growing it the moment it sprouts.
The redstone circuitry is connected wirelessly, it essentially consists of two latches that trigger once the observer detects the sapling, the first one activates the two uber-pistons which move the stone blade, pushing the logs into a few drills, and deactivates after a few seconds. The second latch deactivates shortly after the first and serves to stop the observer from triggering when the blade retracts, which would create an endless loop.