I got to thinking about my previous question about the Bow Clamp's ability to apply even pressure across the length of a glue up and testing with strain gauges- would be nice to know (since I am a skeptic about manufacturer's claims), but I doubt anyone puts even pressure across a glue up with clamps of any sort- you just tighten until it feels right.
What is lacking with the Bow Clamp is the ability to put more or less pressure. If you need to put more pressure in one area (first you didn't do a good job jointing or had some post jointing warp- wouldn't be the first time:-D:-D) you can add a clamp on top of the Bow Clamp. Of course then you are changing the dynamics of it- so why do you need it at all. Second, I often release pressure on one or two clamps in a long edge glue up to make it easier to realign the faces. As DavidF found out you can't do that very easily with Bow clamps. Also, it would be hard to run cauls across the face of a glueup unless they are shorter than the width of ther glue up, since the Bow Clamps would be in the way. It might be better to use regular clamps on the edges and Bow Clamps across the face.
I guess the bottom line for me, they are not a "be all end all" clamping tools, but just another (expensive) tool in the clamping arsenal. I still think they are too expensive for something made from wood (Besseys are too expensive also), and if I were regularly gluing a lot of panels, I would make a panel clamping rack.