Virus A upgrade

[Tek_uk]

Hi all, new member here.
I have been the happy owner of a virus A for many years.
It is fair to say that it has not been used that much of late so have been wondering if I should keep it, sell it or upgrade it.
So my question is, should i upgrade it and if so, to which model (B, C or Ti)?
What are the pros, aside from polyphony, of the newer ones over the original that could make an upgrade worthwhile?

Thanks

Lars