Bombshell, you can still go to any specialist you wish regardless of how you're insured (or not insured) as long as you can afford it. All doctors in Singapore accept Singapore dollars. They still work. But if you're going to follow that logic you really ought to consult with a specialist outside Singapore. It's presumptuous to assume the "best" specialist is specifically located in Singapore. That's probably not true.
Also, the public sector — NUS as a notable example — invests in medical research. The private sector really doesn't do that. There are significant skill and specialization advantages when medical research and applied care are combined. Moreover, it's the public sector that has certain facilities and equipment that the private sector won't buy. The best neonatal intensive care unit (NICU) is probably KK Hospital's. Up until fairly recently the private hospitals didn't even attempt to provide the most sophisticated neonatal care, and they sent all their "hard" cases to KK Hospital. (Assuming KK Hospital had a NICU crib beyond what their own patients required. That was a bit of risk.) Likewise, I probably wouldn't want to go to a private hospital for a trauma wound. I'd want the closest thing possible to whatever medical care NSmen get, and that's in the public sector. And does any private hospital even have a hyperbaric chamber, to treat deep sea diving incidents? Any specialists who care for any such patients?
But OK, no problem, a private specialist (inside or outside Singapore) is on the menu as a possibility. Now, how are you going to pay for that particular care? With some combination of cash, MediSave, and insurance. The insurance part can be "buffet" or "a la carte." The buffet costs more up front, so you have less cash after you buy it. It's a poor choice if you expect you'll "dabble" in the private sector. It's probably a good choice if you expect you'll be a "heavy eater" (use a lot of private specialist care).
I only say "probably" because a private hospital Integrated Shield plan isn't the only insurance choice even if you expect to be a "heavy user" of private specialist care. You could buy (as an example) true "expat-style" medical insurance from global carriers such as Aetna or Cigna. I've had that type of coverage before (employer-provided). It was great. After a US$100 annual deductible (I think) it paid for everything...and I mean EVERYTHING. Even dental checkups and prescription eyewear. A visit to a hospital emergency room in a foreign country? No problem, fully paid. (And that was quite a big bill.) Of course I paid for that platinum plated coverage indirectly (via reduced employment compensation in other forms), but it's another available choice. There are such plans available in the individual medical insurance market if you'd like to buy one.
