i like mine..6600 also. i took off the bar on one foot, and left the bar on the other foot..(have 2 machines,the platinum,and i bought 2 ,1/4" feet)
i want the O2 foot too..i have the little clear foot, and i do like it..but with the O2, it has a wider back end for the wider set apart feed dogs..so it should work better.
i also have 2 seperate setting for the accufeed and the regular 1/4" foot.