So the answer is: using JavaScript in an Action List.

This is what I ended up with...

JavaScript:

var newfile = this.documentFileName.replace(/\.pdf$/i, "") +".docx";
this.saveAs(newfile, "com.adobe.acrobat.docx");

Action List:

Works well. i can press Start and then go away and it will do the whole batch without any human input.

The only annoying thing is that the Acrobat window keeps regaining focus between each file, even if I hide it.

So the answer is: using JavaScript in an Action List.

This is what I ended up with...

JavaScript:

var newfile = this.documentFileName.replace(/\.pdf$/i, "") +".docx";
this.saveAs(newfile, "com.adobe.acrobat.docx");

Action List:

Works well. i can press Start and then go away and it will do the whole batch without any human input.

The only annoying thing is that the Acrobat window keeps regaining focus between each file, even if I hide it. The workaround for that is to put Acrobat in a Space of its own.

So the answer is: using JavaScript in an Action List.

This is what I ended up with...

JavaScript:

var newfile = this.documentFileName.replace(/\.pdf$/i, "") +".docx";
this.saveAs(newfile, "com.adobe.acrobat.docx");

Action List:

Works well.

The only annoying thing is that the window keeps regaining focus even though I hide it.

So the answer is: using JavaScript in an Action List.

This is what I ended up with...

JavaScript:

var newfile = this.documentFileName.replace(/\.pdf$/i, "") +".docx";
this.saveAs(newfile, "com.adobe.acrobat.docx");

Action List:

Works well. i can press Start and then go away and it will do the whole batch without any human input.

The only annoying thing is that the Acrobat window keeps regaining focus between each file, even if I hide it.