I didn't read this entire thread, so if this has been said before, then you can ignore me.
First of all, I'm against the flag icon. In T2, being able to snipe across an entire map, killing a flag carrier who is up to 1000m away and not even close to being visible is complete bullshazbot. That alone is enough to take it out of TV imo. Not to mention that it takes a lot of thought out of both defense and offense, so it essentially makes the game easier, and it takes out a very important element of gameplay. I see that many people brought up the point that it helps people new to the game in pubs, which I can agree with, but I still don't think that's enough of a reason to put it in. However, if it's absolutely necessary in pubs, then at least take it out of any competition mode.
My next point is that this sensor system may be confusing, maybe even more confusing than the systems in T1 and T2, especially to newbies. I say this because it often happens that a generator is destroyed, then repaired, then destroyed, then repaired, etc. all in a very short amount of time. By making the sensor such a focal point in any situation, the same could happen to it. This of course would make iffs flash on and off quite frequently, easily confusing people who weren't sure what was happening. I'd also like to say that if having no iff is the same as having an iff, then why take them out at all? Any skilled player wouldn't hesitate to attack either one, and since this is being done to help people who don't understand sensors, it seems unreasonably simplified. My suggestion is to put IFFs in direct LOS, and in adjacent areas, but if the sensor is down then make no enemies visible on the command screen.