@Acrofales Glad to see this is still useful to someone :)
Actually you're right, this doesn't look right. It was assumed blue = blue = 33%, but I got back to some drop tracking I did a while ago and found I got more like 22%, based on 115 attempts on hard node 8D (LS), or also 22% for the prototype, based on 90 attempts on node 9A.
So I'll update the drop rate to take the "purple" drop rate of 20% instead, and the conclusion should be: buy the prototype.
That's also one of the most depressing items in the whole collection... 2x50 pieces painfully obtained at an outrageous drop rate for... 2% potency??? come on!!