The ABEC bearing rating has nothing to do with skateboarding. It dictates the tolerances to which the bearing is cut (usually within a thousandth of a millimeter, or one-hundred-thousandth of an inch). Do you think the bearing is really going to be that accurate after you put 100+lbs on it and ride it over bumpy streets, sidewalks, etc.? Of course not.
When you buy high-ABEC rated bearings,
"you may notice an improved performance if:
(a) You spend a lot of money (i.e. thousands of dollars) to have your equipment (wheels and board) redesigned and manufactured to suit these high precision bearings. You will need to use some type of shock absorber that allows for absolutely no vibration.
(b) You will have to be prepared to skate on a perfectly smooth surface and make no attempts to use your feet to propel yourself. (Doing so would cause shock loads to the bearings and any extra precision would be lost very quickly).
(c) After you work out how you are going to achieve the above two criteria, you may (and that is only "may") experience a better result than using ABEC 1 bearings after you attain a speed of about 390 KPH (240 MPH) with 65mm wheels and grease lubrication.".
Alright, now that that's over and done with...
ABEC 11 is a brand name, not a rating.