levels of invisibility

I think that the invisibility potion should have levels. Level 1 should remain the same. Level 2 should hide the armor and held item. Level 3 should hide the potion particle effects, aswell as the armor and held item. Level 4 would hide ALL of the particle effects made by the player (eating, footsteps, etc.) and mute all of the sounds made by the player (landing, running, eating, etc.) This would be useful for players who are on an smp server and want to sneak up during a battle. I watched LDShadowLady fight in the purge on One Life (a modded hardcore server) and she had to take her armor off so noone would se her while she was invisible.