So Far, lots of people are flying with ECM on.
As far as I go for classification - (su27)
If i work with radar, I use his IFF to PID a target.
If a jammed contact is going toward the ennemi airfield, I assume it is either a friendly or a retreating ennemi, so i don't engage.
If a radiating jammed contact is going toward my airspace, I send the contact position on teamchat and request for identification on teamchat. If no answer, I shot.
If a non-radiating jammed contact is going toward my airspace, I can't really ask for ID so I try to VID before shooting.
If i'm on a EOS offensive, SA is usually enough for a classification, yet I don't shoot until i get VID. Usually, a plane with racks full and AB'ing toward my base is rarely an allied :D
When i get locked by unknown, i say locked on chat. If no answer I pre-emptively return fire.
Those rules keeps me alive, and I have rarely teamkills. When those happen, I really don't fell guilty at all, yet I apologize politely and try to figure out how me and target can avoid that next time.
But most of my teamkills happen on mig-21bis, which IFF doesn't work 100% of the time, on on AI flights which aren't answering my calls.
The 104th is fun but i prefer RED vs BLUE planes, not mixup of F15s everywhere. Usually, F15's fly blue and sukkhoi fly red so i don't mind but sometime i go fly somewhere else if it's too mixed.