I intend to get the above lens, but have read many negative reviews, but more positives, however, they are all 3-4 years old. The one I have on hand has a serial No. 423xxx, which means it is most likely produced in 2007 or later. I therefore assume that the problems with front and back focus and softness from f/2.8-8 has been solved. Are there somebody with experience for this lens with serial Nos. 423xxx and highter? I have it on hand at USD 1,450 "only".