I've just done a resource import using AD. 

1. The documentation is incorrect how to do this has changed,  It's now done using a button labelled 'Discover Resources'

2. You should be able  to restrict import to a specific OU but when I did this it imports all computers into PMP

3. There does not appear to be a way of stopping the import once it starts

4. Now I have 1000s of computer objects I do not want in PMP

It's not clear how to input an OU, logically it should be the full DN but there is a note on screen implying that I should use a comma separated list.  Well DNs have commas in them. 

I tried the full OU path to start with and this started importing everything.  I clicked ont eh resources tab and the import may or may not have stopped or it could have been running in the background.  I then tried just the OU name, this is crazy as it is possible to have multiple OUs with the same name but different full DNs.  Anyway same result it started importing everything.

I'm not sure how much of a mess it's going to make and how much time I'm going to have to spend fixing it after the import completes.  This is a nightmare!