what should be taught in every open water course?, always do a pre-dive buddy check. Get familiar with your buddies gear, and if you are the divecon on a charter, look around at what everybody is using.
BINGO!!
IMO there is a difference between the 'safety' of a piece of gear and the 'functionality' of a piece of gear. Best I can tell the Air2 is 'functional'... (I have an Airsource... I'm less enamored with it than I was when I originally installed it... but I can't say that it's "unsafe"...)
Given the variety of rig configurations out there, dump valve placement and configurations, tank attachments, weight placements and dumps, wetsuits/drysuits... etc., etc... the desirability of encouraging the good ol' "Buddy Check" is still the best 'first step' in avoiding problems... avoiding little problems becoming big ones... and helping to ensure that 'big problems' stay within the range of manageable.
While there is some obvious advantage to the concept of 'standardized rigs'... there is the obvious problem of 'who's standard'... and 'standardized for what'??? Inherently... even with 'standardized rigs'... it should NEVER stand as a substitute for a good pre-dive buddy check... that's your best and cheapest insurance policy.