I like the watercolors in tubes. I like the gloss I get (not very glossy, but not matte). The carbon seems to be very finely ground and disperses in the gelatin nicely with no oily residue.
I use to use Sumi ink until I finally finished the bottle -- then I could not get the same results with the next bottle (grainy images).
I found that different brands definitely had different pigment loads in them, so I found it best to stick to one brand. I am using 4 to 5 grams for a 750ml batch of glop when using Grahams lampblack watercolor...which is a fairly light load (0.5 to 0.7%). I sometimes add a little Burnt Sienna to it also, but I have backed off of the amount as the prints were getting to warm.