I'd just like to offer massive support for the idea of being able to merge into a single frame/textflow. Sure, it's great to be able to merge one record to one text frame BUT that's so limiting. A textflow can easily be split into multiple text frames, but it's a nightmare of copy/pasting to turn multiple text frames (and it can easily be hundreds) into a single textflow.
I suspect I use the same QXP/ID extension as MikeW: it's amazingly fast and powerful (though it's script based, so not exactly intuitive) and I keep a 15 year old version of QXP just to use it. It instantly converts databases/spreadsheets into really typographically complex lists (think menus, wine lists, catalogues etc) and is very flexible. But the new Publisher 1.9 data merge feature is most of the way there: so close, it's really frustrating. It just needs to offer the choice of single/multiple text frames to offer most of the functionality. (It would be nice to be able to store the 'Fields' settings as a template, too, to save re-inputting them each time).
Big vote for this, please! Like I say it's just a little change ... then I could finally let QXP7 and the ancient Mac mini/SnowLeopard setup go into dignified retirement.