Assuming you are doing this for the customers benefit, ensure the contractual rights to make these changes are there (remember the savings account terms are slightly different, 7 day notice of withdrawal as an example)how often would the change be made?
Few transactions this month may not mean few transactions next month. Changing it back and forth wouldn't work. To change it once, you'd have to continually monitor it and be ready to change it back in the event there are several withdrawals that count in the 6.
Without notice to the customers, I would expect many calls when they get a statement that shows interest income. Also, they may have something that is IRS reportable that they didn't anticipate.
For PR, you might notify those low transaction customers and offer them a switch if they want to earn interest.
Opinions stated are not necessarily that of my employer.
[This message has been edited by Andy Z (edited 12-12-2000).]