Mindshields are available from raiding marsec, though i think you have to be on superhuman or something. Basically the mindshield gives you super psi-defence making it an invaluable tool when facing psimorphs and micronoids, dont know the effect on brainsuckers though (dont think it has any).
Marsec Flying Suits are absolutely amazing, ive got a 4-man(machine) android squad with heavy weapons all with flying suits, they get around anywhere amazingly quick and can blow holes into most places making new and inventive points of entry.
The flying suits are amazing on levels such as the slums and the hydrofarms, however in most buildings raids its near useless as most are indoors, and on alien UFO levels its only really good for crossing trenches quickly, unless of course you blow a few holes in the UFO's armour
.
Overall though they are quite useful but not really for a bulk amount of troops, they are also very good at escaping from brainsuckers and poppers (note brainsuckers can actually jump the whole height of the map, but i think they can only attatch onto a agents head if they are less then 3 height tiles away from the agents, also if there is a ceilng they cannot brainsuck agents (if they agents are just under the ceiling that is).
Androids may be outclassed eventually but they still have super stregnth and health and are the easiest way of dealing with psi-morphs and micronoids as well as being able to bring enough firepower to flatten a building solo while moving the same speed or faster then regular agents.