Pemalite:ODST doesn't require tech 4, it only requires tech 3.

yes but no good cutter will get it tech 3 but wait to get it tech 4, if you get tech 3 you might as well quit since you get steamed rolled by grizzilies, or hawks with no real counter to fight them, plus once tech 3 reactor is destroyed your odst is instantly worthless.  compared to cobra and wolverines that has tech 4 upgrade can still be very effective even if they lose ability to replace them.