The fusion 15, as well as most other SEOS designs, are on diysoundgroup forum. Most don't have a waterfall because waterfalls have been provided for the waveguide/CD, but I have posted the impulse response before, which is a dirty way of seeing the same thing. Admittedly not nearly as good though. Matt did post quite extensive data for the fusion 15 though.
One thing about DIY that often is left out of the equation, is implementation. This isn't easy for the the average user, so many manufacturers make their speakers as turnkey, bullet proof as possible. They want them to work in any room in any configuration. Take Bill's designs for instance. I've heard him say he doesn't design for FR at all. Just even polars and max SPL. And that the user must eq. This is actually a very good way to do it. But the work is placed on the end user. Take MKtheater as an example who has some of Bill's speakers. His measurements look like a roller coaster. Sound like a bad design right. Well, not at all in fact. Just a lot of work for MKtheater. No manufacturer would dare do that because 99.9% of users can't measure and eq like MKtheater and other DIY guys. They don't want the end user posting on AVS or anywhere else "these speakers sound tinny and dry and crappy" when they would sound great with the proper implementation.
Even the SEOS designs (arguably fairly plug and play) have caused a hundred headaches. People don't toe in, or they cross to subs to low, or screw up the XO, or...
But when you DO implement them right, the pay of is huge.