There are actually two forumers here who did aerospace at RMIT,
if I recall correctly.
It's not so much a case of being disadvantaged if you do the degree
at NUS or NTU, but the advantage you have with doing an Australian
degree.
If you apply for PR through the points scheme, your work/education
background will contribute to your points. However, your background
will have to be assessed as being compliant with Australian
standards before being recognised for points awards.
If your degree is from a non-Australian institution, you will have
to jump through all kinds of hoops to get your training and
experience assessed and verified. On the other hand, because
Australian university courses are required to be accredited by the
relevant professional bodies, getting the degree automatically
means that your training/experience is recognised. Note, however,
that the recognition is only valid for six months after you
graduate unless you have started working in that particular field
before that six months is up.
On top of that, you get an extra ten points if your degree is
Australian.
All in all, if your intention is to migrate, go for the Australian
degree.
If you need help getting around the aerospace industry in
Australia, let me know. Boeing is one of my clients, and I have
contacts with aircraft maintenance training institutions in
Melbourne and Sydney and they are hooked up to most of the
aerospace companies here.