well there's 10% difference in capacity but with the 30C battery giving higher voltage under load you may find yourself using more throttle control or breaking traction and unloading more and seeing similar or maybe even longer run times.
Hot Bodies Lightning 2 Pro carbon, Mega 22/30/2, MMM, 4s3-5Ah.
Tamiya F201 carbon, Mamba 7700, MM, 2s A123 2.3ah.
Xray XT8, 1518, MMM, 4s5Ah.
Lots of boats. fastelectrics.net