Here's some interesting information about why it's good, if you can afford it, to keep your mortgage repayments the same as you're paying now.
There's talk about the RBNZ dropping the OCR down over the next few years to 3%. If they do that, interest rates will bottom out at around 5%.
If you have a $500,000 mortgage at the moment, at the average current 6-month rate of 6.75% PA, a 30-year mortgage would require fortnightly repayments of $1,490. This means, that over the entire life of the mortgage, you're paying over $665,000 in interest.
Now, if the interest rate drops down to 5.00% PA but you continue paying the fortnightly repayment of $1,490, the length of the loan drops down to 20 years and six months and the amount of interest you're paying drops down from $665,000 to just over $300,000.... saving you $365,000.
Then, if you decide to put less than half of your mortgage repayments each fortnight ($700) into a managed growth fund earning you an average of 5% PA (after taxes and fees), that would accumulate to just over $190,000 in the remaining 9 1/2 years of that 30-year mortgage term.
That means, with keeping the repayments the same and saving less than half of the mortgage repayments when the mortgage is paid off, you could potentially walk away with $555,000 over that 30-year loan term. In my opinion, it's far better you having that $555,000 than an Aussie bank earning an additional $365,000 because you didn't keep the repayments the same. That could even help you become one of the dreaded Bank of Mum and Dad and help get the deposit together for your children.... or, worse still, the deposit for an investment property.