if you take B2, you cannot choose your doctor. Your current private gynae won’t deliver you at SGH or KKH unless you pay private rates at their private suites (like The Private Suite at KKH, that one $10k+ easily).
My two cents: If you’re low risk and okay not having your private gynae for delivery, transfer to KKH subsidised clinic first (polyclinic referral), then opt for B2. You’ll save thousands. If you really want your own gynae, then stick to private hospital, govt B1 with a chosen gynae ends up not that much cheaper than Mount Alvernia or TMC.