Well, after reading through this I just had to look up the A300 manual.
First, most of the added functionality in the Tech mode is commonly available within general menus on other computers, both Pelagic and other brands. And most of that functionality can be ignored or opted out. (for instance, just don't set a Conservative Factor, and just don't turn on the Deep Stop in Tech mode if you don't want it.)
Regarding the PO2 audible warnings and alarms, I think I read conflicting guidance on my first pass. I am not so sure that setting your PO2 to 1.6 in Recreational mode will change anything for you. You might not even be able to, if I am interpreting this section correctly. (and alarms and warnings both appear to be audibles)
HIGH PO2
Warning, in NORM >> at 1.20 only.
Alarm, in NORM >> at 1.40 only, except in Deco then at 1.60 only.
Warning, in TECH >> at 0.80 to 1.40 (0.20 less than Alarm value set).
Alarm, in TECH >> at Set Point value, except in Deco then at 1.60 only
It looks to me like even in Tech you would have to set to 1.6 in order to avoid audible alerts prior to 1.4. Normally, I would strongly agree with those that are saying to NOT set your PO2 to 1.6. But since your computer is for all intents and purposes warning you off of anything greater than 1.4 when you have it set for 1.6, I would be comfortable with that setting.
In the PADI course we teach that 1.6 is a contingency value for planning purposes, in case we accidentally exceed 1.4. Seems that version of the Pelagic software is using that thought process but with a bit of a different (and confusing) spin on it.
First, most of the added functionality in the Tech mode is commonly available within general menus on other computers, both Pelagic and other brands. And most of that functionality can be ignored or opted out. (for instance, just don't set a Conservative Factor, and just don't turn on the Deep Stop in Tech mode if you don't want it.)
Regarding the PO2 audible warnings and alarms, I think I read conflicting guidance on my first pass. I am not so sure that setting your PO2 to 1.6 in Recreational mode will change anything for you. You might not even be able to, if I am interpreting this section correctly. (and alarms and warnings both appear to be audibles)
HIGH PO2
Warning, in NORM >> at 1.20 only.
Alarm, in NORM >> at 1.40 only, except in Deco then at 1.60 only.
Warning, in TECH >> at 0.80 to 1.40 (0.20 less than Alarm value set).
Alarm, in TECH >> at Set Point value, except in Deco then at 1.60 only
It looks to me like even in Tech you would have to set to 1.6 in order to avoid audible alerts prior to 1.4. Normally, I would strongly agree with those that are saying to NOT set your PO2 to 1.6. But since your computer is for all intents and purposes warning you off of anything greater than 1.4 when you have it set for 1.6, I would be comfortable with that setting.
In the PADI course we teach that 1.6 is a contingency value for planning purposes, in case we accidentally exceed 1.4. Seems that version of the Pelagic software is using that thought process but with a bit of a different (and confusing) spin on it.