Abstract. I don't have an Aeris A300 CS but did consider one when they first came out. It is a sweet looking dive computer. But my understanding is that there were some issues when it was first introduced. Don't know current status. It worries me though that it seems to be drastically discounted from its original price at mulipte dealers and I wonder, with the Oceanic and Aeris merger, if it will continue to be supported.
Having said this, at that price and if I wanted a transmitter, I would be very tempted...
If I were to label them, I would say the Aeris is show where the Petrel is substance.
You may want to take a look at this thread if you haven't already.
http://www.scubaboard.com/forums/aeris/478917-a300cs-oled-dive-computer-21.html