+1 as an option. I personally wouldn't use it because I don't think I'd like the clutter, but I do find it useful sometimes to know what the friendlies around me are in, and have the alt-i function mapped to my stick. It helps me anticipate what the friendlies around are going to do, and also allows me to set the enemy up better for them.
Depending on the friendly's plane type, you drag a bit differently.
Wiley.