I'm planning to use both my letus and my brevis on the same work and I'd like the image to be as close as possible. I'm planning to buy a 72mm HD cinevate achromat for the brevis and I wonder if the letus would benefit from it too. Did anybody ever try this

Why not just use the Brevis? If you have to mix and match I suppose using the same achromat would help. But there are significant image quality differences between the Brevis and the letus so you might have some trouble getting them to be equal.

Now this can be debated to death, but being new here, what are your opinions on the differences between image quality? Head to head that is, Letus Flip and the Brevis for example. Is it the quality of GG differentiating the picture, or what other variables? Thank you.