I third that one...My suggestion is to wait until the Anniversary sale, then CCU your Herald to a Terrapin, then that to the Mercury StarRunner. Since the H & MSR can provide the same data work, but the H can't run any cargo or any of the extra things the MSR can. Which then spares your space turtle. While I liked my space tortoise in my Exploration pack, I upgraded it to a Polaris. I might CCU something else up to a new turtle later.
Compared to the Herald the MSR is defenetly beter: more data space (if I remember correctly), standard cargo space, the ability to carry small vehicles, defenetly a multy crew ship, chess board to challand you Wookie friends....
And let's be honest, even after the few kilos it get the MSR is still a freaking sexy ship....