Not everyone recommends against vivs. The reptile vets at Morpeth for example recommend using vivs at least until the torts are 2 years old so that they can get the humidity they require. There are various opinions on what causes pyramiding but they are of the opinion it's lack of humidity in the first couple of years. More info on pyramiding and why smooth shells often belong to those in areas of higher humidity
http://www.testudo-farm.de/html/formation_of_humps.html