Yes. I prefer not to mix my mid tones so I can keep it consistent across my models and since this is for an Imperial Guard army, that's going to be a LOT of models I'm definitely not looking for 'exotic' nor do I want to go warmer. The majority of my palette will be the Grey Blues and Stone Colors Triads with the Redstone Triad for the models bases so I'm keeping the colors very cool and very muted.
Perhaps this will help. Basically what I'm looking to do is duplicate the paint scheme used on the second model on the left, top row.
So the options right now for my shade are...
1) 2:1 Blue liner to Grey Liner. IMHO, this will help keep the shade from getting too 'blue' or too 'grey'.
2) Either straight Blue Liner or Grey Liner.
3) Midnight Blue darkened with Pure Black. I'm just concerned that the Pure Black will be too strong and overpower the already dark Midnight Blue.