Thank you for the comparison. DeA Steel Blue is one of my regular inks. I just love it. D. Majestic Blue is nice, but I much prefer DeA Steel Blue.
I am always amazed that DeAtramentis inks do not receive as much as attention since they are excellent in terms of behavior and formulation. When I want to try a new DeAtramentis ink, I am confident enough that I will generally buy a bottle rather than a sample. They are a bit on the expensive side, but worth it for those that I use regularly.
I do like many of the Diamine colors and find them to be great inks, and much more affordable. But they are not as reliable; one color may be nicely wet and well behaved, and another color is extraordinarily dry or clogs the pen. I almost always try a sample first, then buy a bottle if I like it.