Actually, tech still is useful after 300, and even more so now, because of the infrastructure discount. Before, if you had all your NS in tech, the max discount would be:
2 * (tech) / (NS = 20*tech) = 10%.
Now the max discount is
2* tech / (NS = 5*tech) = 40% !
Tech can give a huge discount on infrastructure upkeep if you have a lot!