I would use it if it did more than just give you starting juice at the beginning of your life. Although I would totally support having juice sponsors up the rate of juice gain in exchange for slower default rates though, but that could just be me.
Juice endorsement is only valuable at the Gold level and maybe silver. I have other endorsements that need to be gold and silver already. Bronze juice is a waste. And like it's been said, it's only good to you if you die a lot. Or kamikaze juicer. Since Speed and Juice are the two endorsements that are dropped anyway on the field I see no point in using either one in my builds.
why would a person ever use juice. (well if you die a lot) rate of fire increases the number of bullets and therefore the amount of juice gain. (limited effect on certain weapons but still) so yea I never use juice endorsments
It might be interesting if instead of an initial starting amount of Juice on every spawn, the juice gain rate increases OR the juice decrease rate increases (meaning you stay in Juice Mode longer)