As a point of information, I recently changed the fstab entries to state ext4, to benefit from the slightly faster performance that new features common to both ext3 and ext4 make possible. In principle, this should not change anything, since both ext3 and ext4 call the same common fsattr functions but, in case there was a cut&paste error that only affected ext3 and not ext4, this could have some impacts.
As a point of information, I recently changed the fstab entries to state ext4, to benefit from the slightly faster performance that new features common to both ext3 and ext4 make possible. In principle, this should not change anything, since both ext3 and ext4 call the same common fsattr functions but, in case there was a cut&paste error that only affected ext3 and not ext4, this could have some impacts.