I actually just removed mine last week. Once you get good with landings and takeoffs and you are hovering above a few feet without incidents you are probably good to remove it.

I had it on for too long. The last two packs I flew before removing it I practiced up good on t/o's and landings then snipped it off. The heli flies better without it but I am noticing how much I was looking at the balls for determining orientation.

Once you are proficient in a hover you should probably ditch it.