40 is all you need...I have 2- VX-IIs...I can easily see to shoot 15-20 minutes after legal shooting light...And if you are over 40, your eye will not dialate as large as the exit pupil of the scope....

If you want to help your low light shooting...go with the Heavy Duplex Reticle...I have had mine replaced and will tell you its not the target that fades at last light, its the reticle...