I see where you're coming from, but am not changing ship stats based upon it. Earthling is more than a speed bump against the ever-hated Kohr-Ah, while totally helpless against Chmmr. Also consider that Earthling is very cost-effective in vanilla UQM, where no experienced player even uses Ur-Quan.
Ur-Quan that isn't advancing behind fighter cover isn't playing against Earthling properly. A few tips on how to take advantage of this: When a squadron of four approaches, don't turn on the PDL the moment a fighter enters your range. Wait for at least two, preferably the whole squadron, before cutting loose. You'll get hit, but it's still much more energy-efficient. If Ur-Quan is spamming multiple squadrons and hanging back you won't be able to do this, but you should be able to hit the unguarded mothership with a few nukes.