After looking at the tread differences, it seems that the 408 may be somewhat of a danger on wet pavement. It looks to me like the rotation and tread would pull water into the center of the tire causing hydroplaning.
If you track down the thread on rust running out of the swingarms you will find that the answer to that issue will also answer your concern about tread patterns and wet pavement. I believe one gentleman who complained about the rust dripping out of his swingarm was told to
avoid getting the bike wet. Sounds like another excellent answer, in fact one of the very best in the long tradition of outstanding answers to customer complaints. Little did we know that not only are these bikes not waterproof, they're not even water resistant. It's amazing that no matter how long some of us have been around, we can still learn something new every day!
BTW, if you read the bulletin closely you will notice that they really don't say the tread pattern was backward and that they are fixing the issue by flipping it 180°. To do so would be an admission that there was a screwup, and they would be compelled to replace all those backward tires rather than using up the inventory first. So they indicate only that the change
may improve abnormal wear for
some riders. Kind of a backhanded slap at the owners of the bikes, as if something they are doing is the real cause of the problem but in Harley's never ending quest to satisfy customers they decided to change the design of the tire to help out. IMHO, the tread pattern looks goofy either way, and I still wonder if the change really is going to make a significant difference in cupping. I somehow think this is another of those smoke and mirror "fixes" to appease folks for a while until the next big issue rears it's head.
Jerry