Silver may give you an advantage if the seats aren't snapped up by those willing to pay. Your height is also advantage, and check-in will take it into account if those seats remain unsold. If you make it to Gold, there's more chance of getting an operational upgrade but can never be expected or demanded.
The whole subject of getting more space because of your own physical dimensions (be it tall or wide) is a touchy one, and I'd hate to offend anyone. Unless Virgin introduces a new Economy cabin (see the separate thread for speculation about this), the seat pitch as it stands is not really that suitable for everyone. However, they clearly advertise it, so as a paying customer your potential choices are to (a) endure it, (b) pay extra for exit rows or the next class up, or (c) choose a different carrier that offers product more fitting with your needs.
The VS policy on charging for those prime seats has had a mixed reception. I can't say I'm totally thrilled by it myself, but then if there weren't people prepared to pay for those seats then they wouldn't have the policy.
Maybe it's better to look at it this way. Virgin now have 4 classes; Upper, Premium & Economy plus this new Economy-with-legroom available for £50 each way over the base Economy fare.
Aviation generally is pretty unique in the way products are sold. In the economy cabin of every aircraft there are some good seats and some bad seats. However, you buy tickets not based on their position in the cabin but by seasonality, length of time before booking, capacity, monopolies and a hundred other factors. When you get to check in, the seat you get allocated has nothing to do with the fare you paid - so someone on an N-class fare who paid £195 could be sitting in a much better seat that someone who paid several hundred more for a full-Y fare but be sitting in a mid-section with a entertainment system under the seat in front. Is that fair practice? Probably not, but it's the way all airlines operate. Charging for the premium seats in the cabin allows those who want to pay for more space to have it without going the full step of Premium Economy.
Just my 2 Euros worth...
Pix