Thanks for your input, there are some good points there.
Firstly I agree that they should have a worse save, like the hellhound that has its flame canisters exposed making it more vunerable, a moving bomb should be more vunerable too. 6+ Seems a little pointess especially with a sqaud of just 8, so I think they should get no save. Like you said, no point wasting resources on them!
Secondly, if they now have no save then they will be very easy to kill, which means increasing the points too would make them too costly. Even if they deep strike they cannot hurt any unit until their next turn, they explode in the assault phase and not even tau jetpacks allow you to assault after deepstrike. So you get one turn of shooting against T3 units with no save, not really hard to kill are they? So that wych squad can shoot them all down or that guard squad etc will have no problem.
Thirdly, reducing the squad size to 4 seems more practical and probably a good idea, but with allowing only one squadron to be fielded it is always nicer to let the player choose, and do like you say, give each drone a points value.
Finally, I tried to make each drone so that in battle a plasma drone would kill the same points of marines as a firestorm would do guardsmen.
All in all I think they are becoming more well rounded and playable, i have got a few of my friends using tau and trying them out, early indications show things are looking good.