Just mentioning I find it very difficult to beat Tau as one of the few Eldar players out there ( from my own experience) I cant seem to really hurt any of their formations. Be that water or earth cast fleets I am totally overwhelmed by good accurate firepower or many escorts with many bullets? Shells? Whatever their called there are many of them and they often get through my holo-field's. I do notice that their vulnerable to lighting strikes after their shields are down but unfortunately lighting strikes only disable subsystems. I've had good success with torpedoes, but only when some novice Tau player doesn't bring ships with fighter bays. Of the three times I've been matched I've lost twice and won once due to typical scum bag torpedo tactics
, but other then that I often have to disengage since I cant really hurt them.
I'm currently experimenting with different favours like Ulthwe since psychic storm and big death ball Tau fleets are and obvious attraction. However that requires me to drop their shields in some form meaning I have to close somewhat and I've heard manta strikes have high damage potential. However as I close I can be attacked, shot, etc but with stasis and storm the pay out could be huge.
If there are any more experienced Eldar players around feel free to add tactics or experiences with fighting Tau