Open Baffle. Why are they mostly limited to DIY?

'Well, they are different, they are large, and they need a lot of power..'

Yes, can be, not necessarily. Single driver full range OB designs are neither large nor inefficient. I think the main reason for the lack of popularity is esthetics. They "look" too simple and too crude for most people and WAF is below the line. They are also not very versatile and sound best only with certain type of music and certain upstream gear. I just recently built a pair for the first time using the Tang Band W8-1808 full range drivers and they sound real nice but only with jazz, blues, folk vocal  type of music and at moderate volumes. Could be my amplifiers since all I have are high powered SS amps.

david_ten, my remark about the versatility of OB speakers was admittedly only limited to single full range driver designs. The multi drivers like Pure Audio project, Spatial or hybrids with sealed box woofers like Tekton OB, etc., are much more forgiving in terms of music genres that sound good even when played loud.   

atmasphere, thanks for the tip. I read something similar in Nelson Pass's technical article about current source amplifiers and full range drivers. Makes a lot of sense.