This page describes a strategy for moving banking transactions between Quicken 2006 data files using QIF import/export via a dummy account.
Update Jan. 17, 2007: An alternative method for moving transactions is to add an "Account Header" to the exported QIF file by manually editing it. Then, it will import directly into the destination account. This method may be easier than the method described below. It is described further in this article: Import QIF Files in Quicken 2005, 2006, 2007
In Quicken 2006, Intuit has disabled QIF data import on checking, savings, credit card, 401(k), and all other brokerage accounts. They claim that QIF technology is old and the replacement technology, OFX, provides a better experience. This argument seems to be self-serving. HTML is also over a decade old, but people still use it design web pages. Intuit's real reason for disabling QIF import may be because they collect fees from financial institutions that switch to OFX technology.
Maybe the software could show a warning when using QIF, or Intuit could refuse to support customers on QIF. But my opinion is that there was no technical reason why QIF could not have been provided side-by-side with OFX. Technically savvy customers are able to work around the potential issues, such as duplicate or missing transactions.
QIF is still reliable and simple for basic functions, like moving checking, savings, and credit card transactions between data files. One can no longer directly the migrate the transactions, but there is still a way to do it, because QIF Import is still available for Cash, Asset, and Liability accounts. The procedure is described below. Warning: Intuit likely does not support this method of moving transaction data. Use it at your own risk.
You could also use a temporary liability or asset account to import checking, savings, or credit card transactions, where your financial institution only provides QIF export.