I run a 5 box team and usually do use them for the old world stuff. My main is a Paladin/Tankadin and ironically I just solo the ZG bosses because of the mind control, lol. Just easier... Got my Raptor finally after 6 months, still need my tiger!

Shoot if you wanted to go on the real cheap all you need is an 80 Paladin to do all the old world mounts and the only achievements you couldn't solo are AQ40+BWL. You can't multibox BWL or AQ40 so it doesn't even matter in the long run.

Otherwise running 5 toons is a blast and opens up worlds of possibilities.