Dont overstretch, I kid you not. Your wife income 40k is not enough to sustain your family at all shd sth happen to you. Its gonna be really stressful for you then. Just get Jumbo, dont get condo. 1.7m really gg to you with the amount of loan you gonna take and cash to forkout. Did you calculate how much total interest you have to pay over 30 years? It will shock you.
I did a quick calculation for you for the $1.7m condo, rounding up some figures. Assuming you sell ur existing HDB flat for $600k, minus your existing loan, you get back close to $400k. Means you are gonna take a $1.3m loan.
Applying today best interest of 3% over 30 years, you annual repayment including interest is approximately ~$66k a year or $5500 a month. Go calculate how much cash you need to top up aside to the OA you receive every month ($1450 if 35 and below), you need to fork out ~$4k cash every month (this is more than your wife 's annual income or 1/3 your income.
Now, for a $1.3m loan, guess how much interest you would be paying assuming interest rates remain at 3% PA? Approximately $680k, means your condo costs $1.7m + $680k = $2.38m
$680k, you can prob send both your kids overseas to Uni minus accomodation.
Gd luck!