i don't know abt the job responsiblities but has a friend in
there who spent 6 years of serivce and doesn't get to renew
contract. Reason could be due to average performance but
dammm....what and how much u can performance in this kinda of
routine daily job. My own opinion will be that they don't need your
loyalty, maybe they need new blood with low start salary, Of
course, maybe my friend was too honest doing his job only that
doesn't suck up to officer etc....signing on is not as good as in
past now. They get very realistic this day that doesn't appreciate
your 6 years of service, i guess loyalty doesn't come first in
their criteria...... 
just my very personal opinion.....just feeling unfair for my
friend....think twice before sign on.....the world is bigger than
you thought and there's many others thing u can do beside sign
on.
Signing on if u really need the cash to carry on studying or keep
on upgrading yourself etc. U never know what happen after 6 years
of service.