Well the compressors are, they should have the MTBF around that of a freezer when using the standard gas, but the GT uses r404a which stresses the compressor more and so the life is likely to be reduced.
Lifetime is probably affected by:
Working temp of compressor (depending on gas used, fan settings and ambient)
Heat load on compressor
Number of starts you do.
Which is most important i dont really know, but i think if you are looking at MTBF then it would be good for people to post how they use their unit, eg starts per day/week, fan settings, how hot the compressor is if they know, ambient temp is likely to be that of the UK for most, and what you are using the unit to cool.
G