So my interest was piqued and I was looking at these cabs.
I'm quite impressed with the designs, but I think I must be missing something with respect to the cost/value proposition. I am seeing the pricing for the unassembled cabs on speakerhardware.com. I've never played bass so I haven't priced out "bass cabs" but I can't imagine they'd be that much different from a guitar cab. I've found an empty 4x12 assembled cabinet for $170.00 (without shipping) - with tolex or without, but then adding 4 WGS speakers is at least another $300 after tax and shipping. I then still have to paint it, check the bracing, add protected corners, casters, handles, etc...
Regardless of the path one takes, it seems like at the end of the day, whether you buy a fully assembled, painted, tolexed, speaker mounted and wired cabinet, or if build it yourself, mount the speakers, add hardware, and wire it up, you're still out at least $600. The difference is $600 and a whole bunch of one's own effort and tools, vs $600 and "let's jam!".
I've been able to source Avatar and Randall 4x12 cabinets with Celestions in them for around $600.
Do other people find that the whole DIY part of it is worth the effort part? For my part, I actually prefer undertaking the DIY, as I have come to believe that I end up having a unique cabinet/amp/pedal/whatever and that the piece of equipment I have when I'm done ends up having cleaner workmanship and greater durability. But I don't know that I can expect that most other people will make the same calculation. I tend to believe others will say, "Why the hell am I spending my time doing this when I could be jamming/practicing/getting high

etc...?" (which I also think is a reasonable question.)