Anyone considering reflector options may be interested in the study carried out by QinetiQ as hosted here on yachting and Boating world: http://www.ybw.com/pbo/pdfs/radar_reflectors.pdf
The study was commissioned by the MAIB after the sinking of the Ouzo. It examines the performance of a number of reflectors on the market, including the Sea-Me. What is very striking is the degradation of performance of most reflectors at even quite small angles of heel. Also note how the Plastimo tube reflectors perform - even the bigger one is pretty much useless even when virtually perfectly upright - and I have seen these fitted to numerous RIBs.
The Sea-Me performed pretty well and I think it's a good option compared to a passive reflector, assuming you have the power required. it also looks a whole lot better than an octahedral bit of tin bolted to your A-frame! It won't work on S-Band radars though.