A lot of XF nibs can feel scritchy or sharp. another thing to try is running the nib on a paper grocery bag or a similarly textured paper can smooth the feel of it.
De Artamentis Document Black and Platinum Carbon Black do everything you describe. I don’t use anything else now. These are waterproof, smear proof, fade proof, feather proof, practically bleed proof, reasonably quick drying, fully saturated, lubricating and have great flow. What else could you want?
They don’t flush easily but if you don’t change ink it doesn’t really matter.