I'm not sure. if it was available from the start, I might have said "a bit better than a rookie, but worse than a veteran soldier", because then it would be an early-game possibility, but since it doesn't level up, you wouldn't use it too much.
but if it's a later-game tech, I'm really not so sure. it needs to be powerful enough to be useful, but needs drawbacks, too. perhaps if it only has one fixed weapon and cannot use inventory (and thus no items), that's drawback enough? combined with not getting experience, of course.
oh, and I don't know about "elerium chip". in the game, there's no indication that elerium is anything other than a "fuel". the UFO Navigation does not use elerium. so if you need to invent a new chip for the advanced android, perhaps you should rather add something like "advanced alien computer circuits" that is researchable after UFO Navigation? or maybe even after researching a cyberdisc or sectopod corpse?