The only unintended issue I had when I set the respawn to 0 on my vanilla server was that people instant respawn when they are killed in a vehicle or grenade...anything that kills you without revive chance results in instant respawn.
 
I actually set the revive time to 25 seconds and the spawn to 5 seconds to make the time down similar to stock, more time to be revived in a firefight, but you feel like you get back in the action much faster and you still have some seconds to pick a kit and change spawn.