Actually, with profile links you don't need to be active. One of the main cons of profile links is they might be short lived if you're on an active forum. Mods might clean out all inactive members. Another downside is that they could take a while to be indexed by Google. Many will argue that no link juice is passed on, but from my experience and 1000s of profile links, I can tell you that every time I create a group of profile links, I see movement.
They can be hit and miss with their longevity. You may get lucky and the links themselves might stay around for a long time.