jtoh:Getting into NJC and NUSHS is definitely easier. Especially for NUSHS which is purely DSA Academic only. A Math Olympiad Gold or Platinum practically guarantees you a place.
In my opinion, getting into NJC and NUSHS is not necessary easier than other schools. It all depends on the strength and attributes of the child and how well they match those sought after by each of the schools. Both NJC and NUSHS also have a smaller intake compared to other IP schools.
By looking at the number of applicants and the number of places available, one can guage the chances of getting in. In NUSH, there are about 1800 to 2000 applicants vying for 170 places. In RI, there are about 1000 + applicants vying for about 450 places.
While a platinum in math olympics almost guarantee a place, a gold does not. A gold medal holder will still need to pass the first test given in NUSHS before he can move to the camp. The test consist of maths AND science. A gold holder in math may not necessary do well in science. There are some gold awardees who do not make it pass the first round..
There are only about 70 platinum holders each year. Most schools welcome them with open arms. You will find most of them in HCI / RI / NUSH. It is not easy to be a Platinum awardee. Many GEP students do not even get a bronze even though the GEP schools send the most candidates to the maths olympics.
For the GEP students, the chances of getting into HCI and RI is actually higher than NJC and NUSHS. This is because HCI and RI (and most IP schools) have a different route for GEP students from the mainstream ones. The GEP students do not need to sit for any test and go straight to the interview round. There are also more places preallocated to the GEP students in these schools. So you find that the GEP students applying to HCI and RI focuses on preparation of the interview and portforlios whereas the others need to pass the admission tests. I understand in NJC and NUSH, there are no special route for GEP and no preallocated places for GEP - they have to compete on equal footing with the other mainstream applicants.
If you take a look at the GEP primary schools, you will find that most of them have activities to prepare their GEP students for DSA. This is virtually non existent in the mainstream schools. Indeed many students and parents from the mainstream schools are not even aware of DSA.