It should be done only if you are certain that transferring your loan from the current bank to another, does not carry a heavy penalty.
Although you might have purchased the home loan or a personal loan etc., at a teaser rate, transferring to another bank which offers lesser interest rate does not guarantee you lower EMI payments, if you add up the processing fee, legal fee etc., its going to account for a good whole sum getting out of your pocket.
So, if a 1-2% change in the interest rate, should not affect you much as it is likely that with the constant changes in the banking policy, rates are bound to be stabilized across banks.
Considering the fact that if your banks rates go up faster, you can consider changing your bank, but considering the transaction cost and the whole time cost it takes, its best advised to stick with your existing banker.