Well, you need to ask yourself these questions.
1. Can I afford to keep the Virus?
2. Would you be happy selling for less than you paid for?
3. Would you be content using mostly the same synth for all your songs?
3. Most importantly - Do I still enjoy the sound of the Virus?
It depends on a lot of things.
The first thing you are going to do when you get your A6, is not turn your virus on for a month or two, maybe three. This is expected, this does not mean however that it is better than the Virus, but rather more interesting for the time. Most people make that mistake when acquiring new gear. After that phase is over, you may or may not wish you still had the Virus.
Noticing the setup you have in your studio, it seems like you're interested in producing mostly electronic compositions.
As an aspiring electronic musician myself, I would say the benefit to keeping the Virus is simply having another tone to work with. Using different synthesizers keeps your music from having that "Sameness" feel to all the tracks. It does not really require tons of synths, but I think you have enough now to make some great tracks. Many of the members of this BBS themselves have a different selection of synthesizers in their homes/studios. Another benefit of keeping would be having something else to switch on once in awhile, when you get bored. It's also fun to try programming sounds your trying to achieve into a few of your synths to see which one represents it better.
It seems to me your setup would look ideal to a lot of people. 2 nice analog mono's, your soon to be Andromeda, your really High End Virtual Analog, FM synthesis, and your sampler.
If I were in your position, I would not sell -right away- unless financial situation dictated otherwise, and just compare them yourself.
In my situation however, I like to have a different assortment of noise machines
I hope that helps at least somewhat.