I know you made this post sometime ago now but just for your future information. I have a dive centre on Pico in the central group of the Azores we offer manta diving and shark diving and yes we are rebreather friendly, I am a rebreather instructor and dive closed over here which is amazing with the marine life! We have Poseidon MKIV units for rental. We have sofno 408,797 and 812 along with boosted oxygen and helium. If you would like any info please feel free to ask or if you know anyone else wanting CC in the Azores please pass the word info@divetheazores.co.uk