Right now my car is still stock but I'm leaning toward the VAC. Assuming their claims are accurate (i.e. only the timing of the fuel injection is changed, and no additional fuel is used) it seems it won't affect the lifespan of the DPF over the long haul. I'm not looking for ridiculous gains, since the car is fun enough even in stock form.
If I got a JBD I'd probably just leave it at 65%. Also, if the JBD is telling the computer that a different amount of fuel is being used vs. what's actually being used, then it will skew the computer readings, won't it? i.e. indicated fuel economy, distance-to-empty, etc.
2011 335d / Deep Sea Blue / Saddle brown / sport / premium
2008 BMW 135i / 6MT
2002 Z06 Corvette