You should never switch out tanking gear for DPS gear - It's just not worth it, not for you nor your healers mana.
Holding aggro for a Paladin is no problem at all - if you have problem with the initializing threath just pop CD's like this: Wings - AS - Diving Plea - SotR and you will have aggro enough for a mage or warlock to burn a 20k dps burst..
Other then that, I don't like that palas almost need 9.5 sec to build up a stable threath.. well well.
Also, I havn't noticed any change in my dps.. done about 7k all the time.