Ghost, I am a fan of pretty much all things SEACAM except their strobe arms. The arms are robust but too negatively buoyant. The clamps are very cumbersome to work; this makes strobe placement more difficult than it needs to be. In addition, they are extremely expensive (like all SEACAM products). I much prefer my ULCS systems.
Furthermore, I am not a fan of STIX system predominately because the threaded fasteners (screws) that secure the ball-ends frequently back off. Many have suggested "band aide" fixes for the STIX fasteners (e.g. lock tite) but it seems to affect the ability of the user to add/remove floats which, in my mind, was the real advantage of the STIX system. If John can remedy the fastener problem than I think that this system has very good potential.
Lastly, I know many UW photographers that love TLC products. I have never tried TLC personally.
Hope this helps... 