I think the risk factors, namely, interest risk and property price risk, the first one can be hedged or diminished anyway, since the interest rate goes up, it's always a good deal to get a relatively lower rate mortage, in the case interest rate falls, it generally indicate a good state of the economy, so the price for rental will be higher, the money collected on monthly rental fee will compensate the loss of a higher mortage payment.

The only investment desicion should hence base on your expectation of the future real estate market and your financial plans, if as many analysts predict, there would be a rise in the real estate market, it might be a soundy choice to buy some properties, as long as you can afford. Carefully choose the location and the environment.

Since I'm too much away from a pratitioner's side, I over-assumed that the mortgage payment rate would be based on a fixed rate basis, sorry about that, in the presence of a floating interest rate, the size of the movement and its correlation with the concurrent interest rate should be taken into account. Once the interest rate hikes, would the mortgage repayment rate rise for the same amount or same in a proportional measurement.

In a word, once working with interest rate, there is always a lot to be interlapped with government policy, I bid in local investment environment, no wild behavior should happen between interest rate and mortgage rate. In addition, the repayment plan for a mortgage loan should also be worked out before you take the loan, and should be updated with your ever-changing personal financial plans. Sometimes, in a foreseeable interest rate rise or a foreseeable rise in your personal income, early retirement of the mortgage could be taken into consideration.

Well, for the low interest rate and good economy indicator part, I think I jumped into the conclusion too abruptly. On one hand, a more flat low interest rate indicates low inflation, robust stock market, healthy economy in general. While applying to any specif market condition, this rule always neglect a lot of facts. When economy is in the curve of a recovery, interest rate should be higher, as it calls for reserve for the future. Remember sometimes in last recess, the interest rate is also low, as the government tried to stimulate the consuming, as most S'poreans or even Asians tend to be more conservative about saving, and less reluctant to spend in a glooming economy. so the interest rate may also work with a culture context, haha....

All analysis makes things complicated, as I believe, sometimes, when you invest you need a little bit more luck, if you still firmly stick to your own intelligence, better look over a longer time horizon, the accumulative returns would be more significant to predict.