IMO, for actual balance, Turtles would require a few Nether Stars.
When's the next Gregtech update?
I don't think they're overpowered, I think it's good to have something that fills up the early-midgame tier. Gets kind of annoying when every mod starts at around late gold tier and early diamond-tier. Then you just have to play vanilla until you get to the mods..
I do however think that they should use fuel not only when moving, but also like when melee turtles are attacking. Or even a bit of coal to do certain things like programming and getting things from pastebin. I think they should take a little more work, but not be endgame things. Really though, making things require Nether Stars when they don't involve mobs all (except for melee turtle, that should require one for 3 melee turtles or something) doesn't make things more balanced or difficult. It just makes it a huge pain for tech-oriented and Peaceful players. I mean, it's fine if the Charged Gravity Gun requires it, because it's really good. It's fine if a sword or really good armor requires it, because it directly relates to mob hunting. But for instance, a forestry tree farm, which just grows trees, isn't. It'd make sense to nerf it and make it require double the amount of ingots or raw materials, but not something in the combat endgame.
