Korath spores in GC2 were very OP. It was too easy to rush research spore modules and sit here enemy homeworlds with colony ships and then upgrade them to spore ships and catch the enemy unaware and soon have a couple new HW's greatly adding to your starting power and also your influence while crippling the AIs you attacked.
I hope to not see spore modules in GC3.
Yea, they were cheesy, but that's why they were fun. At least the AI didn't do the on-the-fly upgrade, that would've been annoying...