My boat's about 7500# and I don't use it except for braking sometimes.
I say never, but every now and then it'll come in handy if I'm in a situation where I changing driving conditions a lot, like real slow up and down big hills (around some lakes) and curves. It helps to use for the downhill side.
It's not like the old OD days of use it when it's not staying in and is hunting. You'll likely be lugging too much and need to use it instead.