Synthesizing duplicate synapses should retain rarity
A little surprised this hasn't been offered but I find it odd that synthesis resets the rarity to common. It feels like the system should allow parallel upgrading as you progress. So that it takes the same number of Twin I copies to get to a Twin III - Rare going either route. Allowing me to get to a Twin II - Rare synapse for some time before I decide to work towards the Twin III - Rare.