One thing to remember about Paladins is, they will be essentially useless as AOE tanks until the server matures a little bit and you have shield spikes up on the AH to purchase. A huge portion of their aoe damage comes from a shield spike, and not having them makes them go from being able to aoe grind 20 mobs, to not being able to really aoe grind at all.

So, paladin viability as a maintank for aoe grinding instances will probably depend on how hard you are pushing content. If you're hitting level 25 a month in, you might be able to find those shield spikes as your paladin starts to really come online as an aoe tank. If you're hitting level 25 on day 2, you better hope you get those plans yourself