I must say i find the Silent Hunter strategy somewhat unrealistic.
I find the doggies (forgot the name, sorry, i will just reffer to them as doggies) that it opens the path to not fitting to the whole concept.
Tau starts of with massive firepower and is clearly very good against infantery/heavy infantery and has many solutions to that. Kroot comes to add to that already inf supperiority a CC unit. ok, works fine with me. but doggies are too much!! better kroot? i find them dull and redundant. and not opening the other path (vicious attacker strat) means you dont get the good mix of antivehicle units. and i am actually quite worried about the antivehicle capabilities of this race. i hope i am wrong, but with the demo units, some artillary and some tanks/dreads used right detroys any tau army with no casualties.