If you get there early enough, the diamond lot is not an advantage. In fact you will be required to walk to the entrance. The diamond lot is not serviced by trams. This may be a disadvantage if you have put in a long tiring day at WDW.
On the other hand, If you arrive late, there is nothing like up front parking. Beware though, there are blackout dates on the diamond pass. Check with your office to find out when those dates are.