There is no doubt that the physics of a 10" JL woofer in the same-sized box as the 8" BSW design are attractive. Now, if the 8" is super-quality, then that may narrow the gap.

In any case, relatively small short-throw woofers in tiny sealed boxes are only going to go so low. Any differences will be fairly minor and you would probably have to hear them side-by-side to know the differences.

Also, some speaker designs may go lower, but not be as accurate. For non-hip-hop music, accuracy is going to be more important. You want both, of course, if possible.

All of these designs are hugely better than the OEM system of not having any bass at all.

Not that it is exactly the same comparison, but my Essam system is only a bit better than my previous 8" free-standing box. That woofer was a quality long-throw design and the box was pretty big, so it is actually impressive that a short-throw 10" in a tiny box can compete.

You can't compare the cost of these subs to those marketed for, say, Mustangs. There you get absolute thunder for less because of the high production volumes and a lot more space. I think the prices are ok for a complex, low-volume product.

I certainly recommend commercially built units for most people who do not have access to power tools and want to get the biggest and most engineered sub enclosure possible.

if I were BSW I would put in a 10 just to end the speculation, even if there was little or no actual sound advantage.

I ordered the six front speakers and we will see about that. More water in the beans for awhile.