My feeling on boundary loading is that you use it where you can. The long pathway/small mouth subhorns I've designed for HT/hI-fi/Autosound all depend on it to provide response in the bottom octave or so. But for pro-sound, where boundary loading is seldom available to you, and large venues make even cabin gain non-existent from 50 Hz up where you really need it, I've made my subs optimized for free-standing via short pathways and large mouths. Danley's concept is fine if you have boundarys that can be utilzed, or if you have the luxury (deep pockets) of having multiple boxes, and the necessary transportation/roadies. But for the great majority of bands and small sound companies that have to make due with a pair of subs rather than a stable it's a concept that has little practicality. As to drivers,I prefer an eight for HT, while for for mid-level prosound a ten is adequate. For pro-touring a single twelve loaded sub seems adequate, but some of my disciples are now in the process of prototyping with a single 15, not so much because they think that they need it but more from just wanting to see what it will do.