Oil contamination and "flash filling" will lead to a potential fire inside all bottles, this phenomenon is not unique to Stakos.
However, the Stako is, from concept, a lightweight pressure vessel with a thermoplastic liner rather than a alumimium alloy one, therefore there is the potential for this to catch alight if filled under less than ideal conditions.
As far as I can ascertain, the reported Stako failure incidents have involved the regulator separating from the bottle, indicating a weak regulator/bottle interface, this quite possibly more a weakness in the regulator material or manufactureing process rather than the bottle itself.
There was the scare over air leaking from the outer casing, this explained as being due to contraction of an empty liner and the subsequent expansion on filling forcing trapped air out of the composite material.
There have been many improvements made in the supply of high presure fills at sites and tournaments etc. There is still the potential for the inexperienced, unaware or uncautious user to flash fill, especially if filling from an unregulated source such as a bulk tank/dive bottle etc.
That all said, many are wary of those using/filling Stakos and they are certainly less popular than they were.