I built a couple of pair of the Coral BLH enclosures a while ago - certainly not as easy a build as a simple BR, or MLTL. Unfortunately, they were for an out of town client, who was understandably wary about shipping the NOS drivers, so I was never afforded the opportunity to hear them.
If you decide to take these on, I'd make a couple of suggestions:
it probably wouldn't hurt to move the driver mounting plate flush with the side panels. Note that this will increase the volume of the driver chamber somewhat, so just do the math to calculate the amount, and fill the bottom of chamber with appropriate amount of wood blocks. I'd also highly recommend Baltic Birch plywood vs MDF, but whichever you use, it would also be a good idea to increase the number of internal braces (to form a continuous line of bracing from front to back), as well as a lateral brace in the horn mouth. (not built in the pictured group, but highly recommended)
and finally, and double and triple check the magnet's clearance to the first deflector panel before gluing up.
The answer to the question captioned in the drawing, is "yes". These are a classic BLH design offered to DIYers decades ago, when the minimal amount of damping material shown was the norm. If you're really uncertain, and would like to experiment with stuffing levels, temporarily screw but don't glue the second side, and seal with self adhesive weatherstripping tape.
http://www.audiocircle.com/index.php?topic=54093.0
