Frigates get better DPS/OP on Thunderhead due to how it scales, and hitstrength matters a lot less because they'll mostly be fighting other frigates. Capitals, however, basically can't use it because it's too flux inefficient for already flux starved lowtech, and hightech doesn't have great weapons to get high hit rate with (except, maybe, PPJ Nova, but every time I try some outlandish build like this it ends up unviable). So far the only build I've seen anyone make that performs well is HSA elite PD Scarab.