Thanks for the explanation on extreme/min maxing Chris. Very well described.
Venerable one...

 Thanks mate.
I believe a Hero is compulsory too. It is the eternal bugbear for my opponents when they use Guard.
When I said reduce GM's, I actually meant to reduce activations that use GM's. I don't want to see stats changed too much.
In your turret list above, how does the Remote Sensor Tower deploy? Same as the others (from War Engines)? Garrison? I've already mentioned that lighting up your own half of the board is fairly pointless for Tau. If you can't light up the opponents half of the board (and especially their deployment zone for the Hero early attck) there's no real benfit to the Tau.
Speaking of the Hero, it is a unit that really annoys Tau opponents here. 200pts to put blast markers on 4 formations is almost rude. Maybe one of the missile attack could be removed (only allowing 3 missiles instead of 6 and only attacking 3 formations)? If that was the case though the rule about only targetting WE if no Markerlight present may need to be changed.
Anyway, we'll see what CS comes up with in time.