I've been diving quite a while topping up custumers' left overs. As long as the deco profile is safe it is doable. As a rule of thumb i was diving 40ish and 70ish. Ean40 has the advantage that one can safely use it for drysuit when diving trimix and bail out relatively low risk from depth when something goes really wrong.
The big advantage of pure oxygen is that deco time is the same weter at 3mt or 6mt at cost of o2 exposition. So if the sea is rough one can easily deco a bit deeper. Disadvantage is that one need to get to 6mt to start decoing safely and air breaks are very important for long deco. Differences in deco time are not signigicant unless diving rich tmx at depth
The big advantage of pure oxygen is that deco time is the same weter at 3mt or 6mt at cost of o2 exposition. So if the sea is rough one can easily deco a bit deeper. Disadvantage is that one need to get to 6mt to start decoing safely and air breaks are very important for long deco. Differences in deco time are not signigicant unless diving rich tmx at depth
