There is one other thing I forgot to mention that may or may not be an issue. At least it is worth looking at.I am very happy with the B&C DE250 in all areas except one. Their packaging for shipping really sucks. They are just put in a cardboard box without any padding. The driver is first put into a plastic bag, then set into the box, but no foam padding is used at all. In contrast, JBL uses a formed styrofoam basket to hold their drivers in the box, which pads them nicely and protects them from impacts. Eminence uses foam in place packaging, which snuggles foam around the driver and protects it. The B&C driver has no protection at all, and so they bump each other during transit and are extremely vulnerable to shock damage.
I don't recall if you got your drivers from me or not, but regardless of where you got them, it might be worth it to do at least a visual inspection. If they're damaged, send them back in for warranty service or replacement. If you can do some measurements, you can check them that way. If not, you might disassemble them and look for debris in the gap.
I've checked several drivers and in every case, I have found evidence of minor shock damage. There are chips in the magnet and small fragments in the bag. Most times, the chips are very small but in one case it was large enough I felt the need to measure the driver to ensure it was working properly. I expected it might not be up to spec, but it was. I've spot checked several, and so far, all have measured fine. But I always wondered how many times tiny particles from the magnet made their way down through the throat screen and into the gap.