3 years on a Colkan new 15.5
2 years and 1/2 on a Boris
No doubt Boris
Main points why ?
If I flood it through the mouthpiece I can recover it, Not on 15.5
Changeable SP through the dive, Not on 15.5
I can do the dive and deco just with the HUD, Not on 15.5
Quadruple redundancy of reading ppo2, just double on 15.5
Boris will keep me more alive with his Alarms messages than a 15.5
I can mechanically isolate Dil or O2 if ADV or solenoid kaput and still add manually gas w/out having to open/close the tanks for 4h deco ! not on 15.5
etc etc ...
Mk15.5 was a Brillant unit in the 80s or 90s but come on let's grow up we are into the 21st century and some technology will save you when shit happen, it will be foolish to ignore them or maybe you like driving vintage cars
Jerome