I'm not sure about the (in)security of VL6. I used it a lot, and for banking too. I can't say for sure that my VL6 hasn't been hacked, but I have never had any problems resulting from my use of VL6. I did however keep my browser (sort of) up to date, I didn't use any other programs to connect to the outside world, no sshd/httpd/ftpd and other deamons that allow connections from the outside.
Newer versions aren't always safer. Every time code is added there's the possibility for error. Not all newer programs/libraries are necessarily safer than older ones, and just because software is old doesn't mean it's easy to hack. I'm not saying that everyone should go around using old software, but I also don't believe that you have to have the latest software to be safe. Installing everything 'bleeding edge' tends to break things worse than hackers do.
I used VL6 SOHO for quite a while, but I upgraded it to VL7 SOHO a few days after this post. There weren't any important/hard to get going programs on there anyhow. Those are all on my VL 5.9 installs, which I still use for arranging my music. I could probably get me a new install and spend days trying to get the latest versions of those programs to work, but for now I'm just happy my old installs still work fine. If it ain't broken I don't fix it. I don't connect those installs to the web though; I never got wireless to work on them :-). If I want to browse I reboot to VL7.