For me, having the vol knob is something that I would rather have over the blend.. cuz honestly, I don't use the blend, I have a habit of putting it in the middle and leaving it there, never to touch it again!
That's definitely an option! I think it makes sense to eliminate controls that you won't use.
But (for me) I'd think twice about giving up the ability to solo the neck pickup; if you get a P-Tone, you're going to want access to that!
In my case (on my Z2) I omitted the volume knob, but kept a blend.
Whichever fits the bass to your needs the best...