I have it on lvl 2(1500 regens) took me a good 14 hours, but its not that impossible.
Prefer energy transfer to be honest, since everytime I run out of energy is whilst, or just after killing someone(or some three

)
Subsequently: I have all power modules maxed(lv2 whilst lvling up nanorecharge)
and I leveled upthe stealth modules:Stealth Enhance, Hunter, Cloak Tracker, Visor, Radar Jammer.
Armor mods at lv2 = Energy transfer, Nano regen ^^
Mweh, I dont really care about Nano regen but I figured people would moan about it eventually
