These fix to the upper tube assembly only, the rocker box still has traditional rigid clamps. When the whole thing is tightened up, then it should be pretty soild, and perfectly aligned!
It does look a neat solution. The only problem I can see is the risk of unscrewing the bolts too far in the dark and letting one drop on the primary
Not very likely though, and you should keep it covered when setting up/stripping down anyway.
I use obsession clamps
http://www.obsessiontelescopes.com/ATM_parts/index.html which are ok, but a little fiddly.
Peter Read at SDM now uses an alternative (and seemingly very good design) that can be seen on this photo:
http://www.sdmtelescopes.com.au/imag...005/SDM5_7.jpg