Yes I am aware of the mandraulic way of working with the SU4 system both M and A modes. In fact I have several of the SU4 widgets which help to keep old units like the SB25 in the fold.
The flexTT5/1 system from PW looks interesting, from what I understand they hijack the comms and broadcast it wireless using their proprietary system. Look forward to the reviews when they come in thick & fast.
I was hoping for a cheap way of extending CLS but the frequency Nikon uses is very high. It surprises me that Nikon haven't produced a CLS hub themselves.