I would imagine you would only need to change the fitting and not the entire whip, at the same time it may be better for you to reduce the pressure available to 3000 in the future with both fill nipples supported.so would i have to change my whip and fitting on my compressor ???????
I know sites like yours who do cater for all walks of player may need to offer both fittings on whips with one of them reduced to 3000psi to improve safety.
It would be easy to make a change over piece that would allow you to fit both bottles from the same whip if required but as I said, it would be easier to reduce the pressure offered.
Do any of your players really need to have a higher pressure fill.
Russ