Jessip, your existing setup is positive ground and if everything is working ok then you might want to consider remaining positive ground. Your proposed swap changes the polarity of your electrical system. Any diode that is installed and intended to pass current with the existing positive ground will no longer do so when the polarity of the system is swapped.
Hey, you may already know you are swapping polarity, but maybe not.
he has not proposed changing the ground .
He is only swapping a polarized capacitor... wired pos. ground
For a polarized battery
... also wired pos. ground
The capacitor can live without a battery
... pre-existing condition.
The capacitor can live in parallel with a battery
.... an option
can live without a capacitor ... the plan
Plus is wired to ground , for both capacitor and battery