I had clips made for $5 apiece by a local machinist. If you made a bunch, it would probably be even cheaper. There's a diagram on Dozin's site somewhere. Then any cabinet can look like Jer's
The HT cabinet I have is beautifully made and the clips do make it very easy to swap speakers, something that came in handy when I blew an E-120, bought a bad replacement one that buzzed when it was installed, then bought an aftermarket reconed one that lasted for a third of a show. That was a lot of bolting and unbolting and I was happy to have the clips there. But if you don't push your speakers hard, you only have to screw it in once, and the clips just look good.
I would only recommend that if you are running E-120s and bolting them right onto the baffle, use more than four bolts to mount them, they are heavy as hell. But that's just a matter of drilling and tapping in a few more T-nuts. And, the holes in the JBL frames are pretty tight to the hole, as I recall, so, you know, measure twice and drill once, etc. Not such an issue with lighter speakers.
The problem with those Lopo Line cabinets is the dimensions are not as tight as the original Dead cabinets were, the speakers are very close together in Jerry's cabs and very tight to the sides, too. And there is a world of difference between an open back cab and a sealed cab. I think the Lopos are closed back.
Like Jeff, I built my first one with a friend, it sounded great, but it was heavy and impractical to move around with the E-120s in it. So I built a pair of 1X12's myself, they looked like s--- but were easier to carry. Then I got the HT with the AVS road case, and it fits my needs.