Torsional loads at the crankshaft increased dramatically in 2007, testing a number of powertrain components beyond their mechanical limits. Components that would have previously run for the life of the machine, now fail with some regularity. The Cush Drive, torque smoothing calibration and SE comp sprocket all serve to reduce torsional load.
The compensating sprocket is designed to reduce torsional load through the transformation of mechanical energy. The SE comp sprocket is claimed to have a 700% increase in torque capacity over the original. I believe that the increased loads generated from the 2007 and later powertrain also significantly impact the lubrication properties required for this assembly to run reliably.
IMHO, with regard to premature wear, the seemingly random failure of the comp sprockets is more likely related to a lubrication failure than to an issue with materials. Also, the manner in which the vehicle is operated has a significant impact on the load and the mechanical energy transformed by the comp sprocket. It seems reasonable that a riding style which “works” the comp assembly hard and often might make the difference between premature failure and normal service life, with all other variables being relatively equal. Then of course there is the lubricant.
Prior to 2007 you could run just about anything for lubrication in the Big Twin primary housing. Based on the appearance of recent failed components, with the burnt lubricant, metal transfer and extreme wear, together with what we know about the 2007 and later powertrain, with regard to lubrication, things seem to have changed significantly.
A redesign of the sprocket would likely reduce reliance on the lubricant; although it appears that there are a large number of machines that do not experience issues, so at this point in time it seems unlikely that this will happen.
It is also interesting to note that in most if not all cases of premature wear with the non SE comp sprocket, the sprocket shaft extension always seems to experience the most wear (as seen in the previous photo). If you open this photo of the SE sprocket, you will notice that there is no appreciable wear on the shaft extension. The splined surface area of the SE extension was increased substantially over the original unit. The distribution of load over an increased surface area reduces the load at each point of contact, improving the resistance to wear. As always, JMHO.