ACHTUNG: Bad News... my #10 has, after 10 years, experienced a vast IG fallout.
I can't get the sediment back into solution, but I suppose that's the aim of an IG ink in the first place. Well, here's at least what I see. You're responsible because it was your idea to whip out #10. Har, har, jus' kiddin', 'eh?
Akkerman's #10 -- what's left in solution as well as what ends up on paper -- has faded. Believe me, when I look at the solution itself plus precipitate in a beaker, there is in fact a great resemblance to Diamine's Prussian Blue. But the #10 scribbling shown here looks way too green. If I (or anybody else) can or will compare the flows, it seems that #10 still writes freer i.e. is wetter than Prussian Blue.
David, I have included MB's Royal Blue because you mentioned that you use it a lot. I use it a lot, too, simply because it is one of my very most favorite blues. Impeccable. Also wetter and freer than Prussian Blue (even if it takes longer to dry).
Here's the scan, using my Herbin glass dip pen on Rhodia's 80 g/m2 (21.3 lb.) paper. Drying times are in seconds.
All in all, I'd sum it up like this (if you don't mind comparing apples, oranges and bananas):
Blue: #10 < Prussian Blue < MB Royal Blue
Gray: MB Royal Blue < Prussian Blue < #10
Green: MB Royal Blue < #10 ≈ Prussian Blue
Flow: Prussian Blue < #10 < MB Royal Blue
Saturation: #10 < Prussian Blue ≈ MB Royal Blue
Time to dry: Prussian Blue < MB Royal Blue < #10