I know too well why phasing is needed, but please be conservative about it, it should only switch if the area is too crowded and possibly not if:
I’m close to a corpse I can loot: “you don’t have permission to loot that corpse” while switching phase
I’m close to a resource I can harvest: quite annoying to fight your way to a mining node just to see it despawn before your eyes
I have “too few” other players around, it should only change if I have “too many”, it’s quite annoying to find yourself a quiet spot just to see hordes phasing in
I’ll also take the chance to point out that every single mining node in southeast Icecrown is bugged, I mean the Argent Vanguard and Scourgeholme area. They either can’t be mined because “already in use” or can be mined but not looted because “don’t belong to you” or can be mined but the character gets stuck in looting position, or just can’t be clicked at all.
They then despawn, I believe this also to be tied to phasing