Good question, but difficult to answer. Yes. I completed a 40,000 image import with all options checked.
A couple of things though. The plugin will leave any "referenced" files where they are and copy any "managed" master files in your Aperture library to the location you specify. Previews will be copied to the corresponding old "referenced" master file location, or the new Lightroom location, depending on the source.
Only files with generated previews will be copied to Lightroom. I also saw several errors about previews being "skipped" because they were "not up-to-date". Could be that the preview just does not exist, or that it could not cope with the size of the preview. Just don't know, because Aperture does not make this easy to know what you do and do not have previews for. I strongly suggest you make a conscious decision to delete previews you do not want (makes the result messy), and create appropriate sized previews for what you do want to keep. So I'd suggest you delete previews, then generate them for all that you need, based on filters. Strongly suggest creating full-resolution previews. You only get one shot, so why not have a full-sized preview.
And it does stack photos with previews. Remember, Lightroom will not stack Aperture stacks. Will only create keywords for them, if the option was chosen, but you can stack them later. Did not have the presence of mind to keyword all my photos that did or did not have previews, so I wasn't able to get a good idea of how accurate the plugin was in stacking previews. Suggest you keyword photos you create previews for so you have some method of validating the conversion afterward, or need to compare output from the error log.
Lightroom DOES NOT allow the use of stacks in the "collections" view. <sigh> So make sure you're using the "catalog" view.
Update: aperture_iphoto_importer v1.0.1, released 11/4/2014, does not copy all previews available in Aperture. You may see the skipped file in the log, but usually, you will not. Seem to have about 25-30% success with the plugin copying over the preview. It does seem to stack all the previews it copies.
Effectiveness evaluated by:
1-Doing a search on the Previews folder within the Aperture library, and deselecting thumbnail JPEGs
2-Doing a post-import search on the master file location for Aperture referenced files and the Lightroom plugin's target destination, and searching for all files ending in _Aperture_preview.jpg
Using a hash-based file compare utility on the Aperture preview directory and the resulting Lightroom stores.
Both methods resulted in identical information. Over 70% of preview files were not copied.