When using 4.01 M33 generally the M33 Driver is the best in terms of speed and compatibiltly. Under 4.01 M33 and i would use the sony Np9660.
Like acerthief says, i do not think there is much in it TBH. I have known some back ups not to work with the Sony driver but WILL we the M33 and Vice versa.
oe isofs -> No idea XD
4.01 M33 didn't had any improvements on the M33 driver since older versions.