i dont think either was really recommended in strict terms for the C5, but common sense applies here, if you are of a heavier weight, then that extra weight will have adverse results on the C5's performance, ie more weight to carry, less speed on average and certainly less distance on one charge of the battery. A perfect example of this is someone who with a battery does 15 miles on one charge, with 2 only does 26 and not 30, the answer is you have to carry the extra weight