@jip
Imo option n1 is out of question as it's gonna be a very hard nerf to any small firebases that otherwise would be unscouted. Not to mention now always knowing what is shielded and what is not.
As for which of the 2 and 3 I would prefer it's hard to say, but option 2 seems quite decent as it still gives you idea that there is a shield there but it won't make it so you get intel what kind of shield it actually is and where exactly it was placed.