Hi Magnus and thanks for your reply, I hop you did not consider my post as a "rant" about previous discussions....I'm sorry for not being more involved in the last years but with 2 daughters of 1 & 3 years old, most of my time and energy is devoted to them.
I will not quote your reply as quotes of quotes of quotes does not make things easy to read.
First, yes, I collect Tau at epic & 40K scale.
OK for your explanation on the Command HQ stand within a standard unit. I did not remember there were some similar situation in the game (despite I play Squats since 20 years and more than 10 years at NetEpic...).
About the Skyray markerlight: for sure, skyray do not need the Turret ability on it's main weapon as it has the AA Ability (that includes the 360° arc of fire). The "problem" is that the skyray marker lights are mounted on the turreted weapon carrying the AA missiles. At the moment, according to markerlight description, it works as a weapon (it has a firing range, a to-hit dice, can be used to snap fire or in fire segments) so I supposed that it also has an arc of fire. There's no problem on infantry/cavalry with marlerlights as those units have a 360° arc of fire from their sizeclass. The only problem is for the Skyray that is the only vehicle with markerlight and I wanted to know if I can use its markerlights to mark fliers ?
About the "AA seeker missiles", I think I should have tried to clarify better my point of view. I think the "AA" as Anti-Aerial for those missiles is not the right term. I think those misiles should be "Air-to-Air" Missiles:
Air-to-Air= Can only target fliers/floaters in 180° front fire arc without penalty.
Third: OK, you're right, I did not look about the chassis but I did not say anything about changing the cost of skyrays. I just compare to others units that have a 100cm AA weapon range and a standard chassis.
I play various armies: IG, SM, Chaos, Necrons, Squats & Taus, I fight against very various armies too and sometimes with a huge number of fliers so when I build my army, when I pick a unit with AA ability, it's for its AA ability, not for the chassis. Most of the army lists have a single dedicated AA unit, you don't have many choice. Dedicated Tau AA Ability unit is the Skyray, with 2 shots at 4+ for the detachment, you can not say that a single or two detachments will protect you from your opponent fliers.
After reading your previous discussion with Peter, I thought you were going to simply remove the possibility from TigerShark & Barracudas to fire their "AA seeker missiles" at flying target, maybe I was wrong ?
Have a nice week-end all