Hi Doug,
as you have noticed adaptive mode is not really adapted to the learner!
Tim give good indications to the lesson module and to a new hypothetical module.
The biggest problem with adaptive activities is the time required to create them! The lesson module permit some adaptive but it will be very long to author your questions with appropriate distractors and appropriate navigation in the questions tree.
If you search forums with "adaptive" then you will have more than 1000 posts, some of these approaching your definition of adaptive.
I am working part time and slowy on that since few years. If you search "adaptive Bernard" you will get about 50 posts about my slow work. But thing are starting to work as expected 
and the generator is working well with simples questions and some more complex. The adaptive part, the navigation is not ready yet but two ways to reach it are tested and worked:
1 - Generation of lesson in xml with controlled navigation
2 - Revealing hidden cloze questions in a quiz adapted to student answer to previous question.
The framework I use is based on Itamar work:
http://moodle.org/mod/forum/discuss.php?d=162866#p715607
All in javascript, nothing to modify in Moodle, works with Moodle versions 1.9 2.0 and 2.1
The project is named Socrate as it will appear as a socratic dialogue to the student!
"Socrate" was created in a SCORM form: you can see a french auto-presentation here.
The file is heavy ( 41 Mb ) be patient.
The new version is on the way to be adapted to Moodle without the SCORM portion in "native mode".
If you have some french reading capabilities here is a long presentation that show the bases of Socrate.
I hope it may help,
Salutations from Québec,
Bernard
