from what i have heard, it was a case of return to the airfield syndrome. though at YKAT, there arnt many options either way.
As for 2 stroke reliability, i have been flying with these for some time, (150hrs) and had not 1 engine failure on the rotax 503 in that time, nor a single missfire either.. the engine has been maintained by the book regardless of what others say about their TBO times and how they can be "extended" i would fly behind the 503 as confidently as i would a Jabiru or Lycoming.
from studying the manuals and engines, speaking to many other fellow flyers around the traps, the most common cause leading to failures in 2 strokes is temperatures exceeding their limits, most often EGT's, other common causes are clogged carby jets leading to excessive leaning out and problems associated with that. or simply not setting the jets to suite the altitude or weather conditions, again leading to heat issues,
from winter to summer, my 503 carby mixtures will have to be adjusted 2 or 3 times to ensure the EGT's remain in the green at all phases of flight.