It's been about 6 months since Warhammer 40k 6th Edition was released (some would say inflicted) upon us and I'm interested to hear how your Tau Empire armies have changed.
To stimulate the discussion, I'll give you an idea as to how my own has changed.
First thing I realized about 6th edition is that Tau Piranhas no longer have much utility to warrant inclusion in any "competitive" army build. This is not to say, I wouldn't ever field them, but here's why they are no longer useful.
In 5th Edition their primary use was in move blocking other vehicles and infantry, especially things like THSS terminators. They suited this task well, because they:
a) had a 3+ roll to stop ramming
b) got a 4+ cover save from turbo-boosting and
c) infantry needed 6s to hit them in close combat.
This gave them a chance of survival and more often than not, they were able to stop enemy vehicles dead in their tracks.
Important changes in 6th edition, nullified their chances of being effective blockers because:
a) no longer have a 3+ roll to avoid ramming - meaning vehicles get to ram straight through them, completing their move and potentially destroying them in the movement phase.
b) are always hit on a 3+ in close combat.
So in 6th Edition any kind of move blocking entails a sever risk of them being destroyed.
Next important change to 6th Edition is the nerfing of transport vehicles due to changes in the rules as outlined here:
a) troops need to disembark from transports to score on objectives.
b) hull points make repeated glancing hits fatal for vehicles.
c) troops cannot move after disembarking from a vehicle, beyond a run move.
This means two things for your Tau Empire forces:
1) No need to spend points on Tau Piranhas
2) More boots on the ground across all armies.
The consequence is this:
Your Tau force can bring more firepower (from points saved on previously near-mandatory Piranhas) and your firepower has more utility (lots of Tau weapons have primarily anti-infantry capabilities and there are more infantry out there these days).
So my force is shaping to have more Fire Warriors, the return of Crisis Suits with Plasma Rifles and Missile Pods, and I've seen Stealth Suits coming into their own.
How about you guys? How has your force changed in the new edition?