I think the VX-2 is a better scope. But not necessarily better in low light. I'd think a 1-4X20 VX-1 or VX-2 depnding on budget would be perfect for your rifle. But the scope you have would probably work just as well. I'd use it for now, if you decide to upgrade later you can.
There are 4 things you need to know about low light optics.
#1, Exit pupil size. This is determined by taking the scopes front objective size in mm's and dividing by the scopes magnification. This will tell you the diameter of the beam of light exiting the rear of the scope and entering your eye. The larger (up to a point) the better. A 1-4X20 scope set on 4X will have a 5mm beam of light exiting the rear of the scope. A 4X scope with a 40mm front objective will have a 10mm beam of light hitting your eye and be much brighter. At least in theory.
#2, Your eyes limits. A person still in their 20's with good vision can open up their pupil enough to allow 6-7 mm of light to enter the eye. Once you start to get into your 40's or older your eyes simply don't work as well and about 5mm is all you can use. A scope that has an exit pupil of greater than 6-7mm is wasted on everyone, and above about 5mm on most of us. I'd want a scope, or binoculars for that matter with an exit pupil size of at least 5mm for low light use. In bright sunlight lower numbers work fine.
#3, The more magnification, the easier to see in low light. Unless your front objective is too small. Going to larger front objectives has trade off's. A 40mm objective is just fine when set on 6X-7X or less, but is pretty useless above 8X in low light. A 20mm objective works well at 1X or 2X and is just barely acceptable at 4X. Going up to a 50mm objective doesn't really help on lower magnifications since the extra light is wasted, but at 8X or 9X does offer some advantage over a 40mm scope. At 10X or more, it isn't any better than a 40mm scope.
The 3-9X40's are the most popular for a reason. They are a great compromise. On 3X magnification isn't too much for close shots, they work well in low light as long as not set on the maximum magnification, are reasonably light and compact and are value leaders.
#4, Light transmission rating. These can be hard to find, especially with low end scopes, but is really the most important. The exit pupil rating tells you how large the beam of light is coming through the scope, but nothing about how bright it is. Most of the cheaper scopes are in the 80-85% range. Meaning 15-20% of the light entering the front of the scope is lost and never reaches your eye. Moving up to the mid level $200-$300 scopes you see numbers in the upper 80's and low 90% range. The biggest difference in the $400-$600 scopes is light transmission ratings around 95%.