Measure current ripple over shunt, legit?
I'm thinking of using a calibrated shunt and then measure the current ripple by measuring the voltage over the shunt, with an oscilloscope.


This is effectively a current probe.
You could use a differential amplifier
or an oscilloscope in differential mode (thereby using its internal differential amplifier.   

By a "current probe" I assume you mean a non contact probe using eg a Hall cell.  This is effectively a floating probe which measures electromagnetic field rather than voltage. Differences in result such as bandwidth are a result of the differing technologies but you are effectively doing the same thing in each case.