My Fodera and one of my BN6s have volume / blend. I do like that this control configuration gives you more control over your volume, but I *FAR* prefer volume / volume.
Tone just matters more, and vol/vol gives you more flexibility to find the right tone than vol/blend.
From my 1978 Fender Jazz to my newest bass, and all the former bases I have ever owned, they all sound more open and clear with both pickups are fully up on the bass than if both pickups were dialed up 50%, then boosted at the amp to have the same volume. The tone is affected slightly on a vol/blend bass.
Besides, what does a blend knob actually do?
If a blend knob is at the notch, straight up... what does that even mean? Is that 50% neck pickup and 50% bridge pickup? Is it 100% of both pickups? Because those are two slightly different tones.
And what if I dial the blend halfway to favor the bridge pickup, what does that mean?
Is that 25% neck, 75% bridge?
Is that 50% neck and 100% bridge?
Whichever the right answer is, mathematically speaking, a blend knob cannot reach the range of tones that two volume knobs can.
Yes, it is convenient to adjust your volume with a quick flick of your right hand, but I really would rather have the tone I want, and adjust my volume another way.
For instance, depending on the venue size, I sometimes use a pedal to control the volume.
Vol/blend has its convenience, but I prefer the tone sculpting of vol/vol.