relative safety
As for relative safety statistics: look at the IATA figures, Boeing figures, ICAO figures, and you will see them expressed as incidents per million flights or flight hours. The IATA 2006 review excerpt below runs...
"The 2006 industry hull loss rate was 0.65 accidents per million flights for Western-built jets, which is equivalent to one accident for every 1.5 million flights—a 14% improvement on 2005. IATA’s member airlines performed significantly better than the global average with a hull-loss rate of 0.48 accidents per million flights, or one accident for every two million flights. There were 77 accidents in 2006, compared to 111 in 2005. Of these 77 accidents, 46 involved jet aircraft and 31 involved turbo-props."
Orient Thai and OTG are not IATA members. One can only wonder what an IOSA audit would do for them.
Having been heavily involved in matters relating to Adam Air 574 , Garuda 200 and OTG 069 over the past 18 months, my opinion is that an IOSA audit process should be mandated by the aviation insurers of all three.