As you've discovered, not all silver cards are the same: BA Silver is very valuable, even though they only call it Silver. In the oneworld alliance it's the same level (with the same sort of benefits) as Qantas Gold and American Airlines Platinum. Make of that what you will.
BA Silver is much harder to get and keep than VS Silver. In fact, my partner was recently just sent a VS Silver card in the post, out of the blue (as it were) - even though both she and I have long since failed to qualify for anything other than VS' most lowly tier.
So if you can get the BA Silver back, you should definitely try to do it.