I never saw any similarity between Tuvok and Spock. Lacking Spock's human half, Tuvok was never prone to emotional outbursts. Despite being very close with Janeway, he never called her Katherine. He didn't seem to have Spock's super-sharp mind, either. He did have a very real mellowness, though. Something I figured comes from being quite a bit older than Spock, and having a family. Star Fleet seems to be more of a career than a life.
Early in the show Soval's only role is to be an annoying prick and his only adversary is Archer and those pesky humans. As he mellows out towards Archer and begins to have other things to deal with he becomes a much better character, and Vulcan. Enterprise also allows us to see more Vulcans and how they behave in groups. Given their logic, their smarts, their strength and their technology you have to assume they could be the badasses of the galaxy at that pont of time, should they decide to be. I mean, who would want to take on a ship full of Spocks? We get to see some of that in ENT, and for a bunch of pacifists they're pretty quick to resort to violence if that's what the situation dictates, and ruthlessly efficient when that time comes.