On one hand, they make great roadblocks, contesters, and general annoyances, built-in to the cost of the Devilfish.
On the dreaded downside, however, they are ruled to give up KP in most events. This can absolutely screw a Tau players chances in any mission that involves, KP, essentially giving up an additional killpoint for the deaths of our transports.
So the question is becomes: is it worth the points to get rid of them? 2/3rds of the time, they can slow enemies attacking a small firebase, block assault lanes, give cover... but on the third, they can lose you the game easily.
To buy SMS for a Devilfish, you have to pay 20 points. While it gives you a bit of firepower, the amount isn't really equal to what you can be getting from an actual fighting element, such as a Crisis Suit. You lose your road-blocking techniques, but gain safety in Annihilation.
As for me, I've been on the fence for this for a while. After some deliberation, I've found that my army needs the extra points in real firepower. Drones are back on my Devilfish to both save points and to run interference for my Broadsides and Pathfinders, buying them some extra shooting turns, hopefully.
Other Tau players; do you have Drones on your 'Fish? No Drones? No 'Fish?
