JC is not 640 strength. JC is 320 strength. 640 strength minus the 320 strength they are replacing. Engi also averages out to 320 strength but lines up very nicely with our cds and there are no useful on use trinkets to compete with it at the raid level at 90.
Oh, I won't be switching either. Just saying that it is better. For that matter, LW is 330 str instead of 320.