Nice paint job, though I will have too say your list is quite unbalanced. The cost for the transport could easily fuel more troops and firepower. Seeker missiles generally work much better if you were too have more markerlights, devastating as they are they might not be as useful as you think. Your HQ, though very powerful, is quite unbalanced. If you want three weapons you might want to take out the Fusion and add another Plasma instead because of the lack of any real powerful tanks in 500 point games, your Plasma Rifle will be able to take care of anything like Rhinos and such. Currently I believe both your Devilfish and Shas'el are going to draw alot of fire. They might go on and ignore your 12 man Fire Warrior squad and take out your Devilfish. By then your HQ will be in range and a scarier threat, so they'll then take that out, leaving you with just 12 static Fire Warriors and some Gun Drones with extremely low leadership and perhaps some of the remaining Fire Warriors from your now decimated Devilfish. Still, you should try it out, I might be wrong. On another note I agree, plastic is good. Though I doubt any Tau army is indestructable. Lets see this army fair against some Necrons...
