I found this:

AR Ejector Mod

What are the benefits and drawbacks to doing this "mod" ??

From what I understand Bushmaster does this on the Varmiter model rifle to make all the brass go into a neat little pile.

I see the possible results of this as being only bad.

A weakened ejector spring will cause the spent case to be ejected with less force.  This could lead to a type 2 (failure to eject) malfunction or worse (e.g. spent brass getting hung up in the receiver).

It sounds like a mod that someone who fires only on a range would try so as not to get yelled at by those shooting next to them - or so they would not have to walk so far to pick up spent brass.  Both NOT good reasons to modify a defensive weapon.

Just my 2 yen.

Chop and modify no spring especially in a rifle meant for more than just the range.If you have a varmint rifle or one just for targets thats one thing but for me no matter what type of rifle I wouldnt go playing around with vital commponent springs,thats just asking for malfunctions and some times worse.

it's a common thing to do to a highpower competition rifle
keeps the brass from going down your neighboor's shooting coat
you only remove a few coils,

It's not needed anymore with the advent of the Wolff XP extractor spring.

with the wolf XP extractor spring, my shells are flying about 9 feet to the rear and right of me. It's better than my Vepr which spits out shells up to 50 feet to the right.