Relax Jazz, I am not exactly disagreeing about the differences with you or others, but as you say, it's about costs, so it is a compromise.

Regarding experience, I should actually ask the same... because honestly, if you have such low views on those BK/BF bearings then I have to assume that you don't use them. On the other hand, I am waiting for the 10th, so yes, I must claim that I have some experience with them, more than you think. OK, only for 1605 and 1204 screws, but none the less... I was not born yesterday just because I ask some questions occasionally.

Anyway, I am NOT saying that those bearings are as good as AC bearings. What made you believe that? All I am saying is that he should wait and see and decide on his own for the final decision. Of course it's good that the alternatives are clear and drawbacks are highlighted, but as been said before, replacing the bearings is easy and can wait. But then again, if replacing means complete redesign of bearing seats to fit AC bearings then it is a huge job for an amateur and also a large one for a pro. It's also a hobby machine, so aiming for something reachable is better than aiming at the stars and never get there.