(UPDATE: more data added to plot)

Measured one!

On the left is the transfer characteristic I measured for my MOSFET that I converted to depletion mode. On the right, I plotted the characteristic from datasheet, and my own measurement of a fresh MOSFET. They depart a little bit in high current range, because my measurement setup is not capable of currents above 10 A (Li-ion cell can't provide much more than 10 A).

The characteristic is not too bad, but it does have a noticeably lower slope than the datasheet one (to make it more obvious, I placed a replica of factory state curve close to the hacked depletion mode curve).