So I have debated for a while over the Grav Hooks system currently in game.
To explain the purpose first:
The Nicasser and the Warden, both of them are ships without capability to 'warp' hence the requirement of grav hooks, these act like a 'Tow bar' to tow the ships through, the 'Mother' ship 'rubber bands' just between the 40k dimensions and the Third Dimension pulling escorts along to get them to a fight.
The TT rules:
The Tau can choose what ships (if any) to attach to the grav hooks and pull into a fight, much like a car with a tow bar, it doesn't need to pull a trailer, that is a choice. The ships have a set value, and each escort costs points to attach. Much like any other race where you pick what ships you want, and they cost points. The only difference being, some of the Tau ships need to 'piggy back' on a parent ship.
Side note (Lore Sake)
On this side note, Tau would never use the Nicasser in a conflict against the Imperium due to them being psychic xeno life forms, when the Imperium of Man find out the Tau have Psychic xenos in their ranks, then they will pursue extermination of the Tau with full force.
Best possible fix to match up with all the above:
Remove the current coding of escorts to grav hooks and add a simple 'IF' function or series of 'IF' functions
IF ________ has Grav-Hook then allow equal number of Wardens, IF _________ has Nicasser upgrade allow Nicasser attachment equal to number of Grav-Hooks
In addition to that also modify pricing so that Grav-Hook attached escorts have their prices and Parent ships have theirs, that way, like in the TT, You attach however many Grav-Hook escorts you wish (if any) or afford.
(All 3 Variants) Emissary=110 points (with them having prow delectors (+10 points)) = 120 points each
Warden =30 points
Nicasser Dhow= 45 points
From what I can tell, this will be considerably easier than editing several models code to not have grav hooks, inserting them into game, coding the AI to randomly select it, coding the custom game system to select it for Level 8 randomly generated profiles, removing the nicasser upgrade from selection, coding new options in the menu for when people wish to purchase it/select it and reducing the prices.
I hope the development team will insert this into the Tau fleet rather than a new model (if they considered it at all)