Nick I'm not sure if it was a reply to ypu in another thread, I know I replied to a similar question recently. I'm not a Mac user, but have been a very keen user of LR for over five years, including transitioning from a laptop with multiple USB drives to a full desktop system.
Even if the automated transfer from Aperture to LR only puts the original image files in one large folder, and rebuilds your Aperture pseudofilesystem as LR Collections, the fact that it includes all of your added EXIF type data would make this a much quicker process. To move the images to actual folders in LR will be pretty quick, since you just need to create the new folder in the folder tree in the LR panel, move down to the collections panel and go to the corresponding Collection. Cmd+A will select all the images, then just drag them to the required folder. This will be much faster than adding back all the EXIF data manually in LR.
When it comes to Smart previews then I think they have a place where you are on the move a lot, using a laptop where you need all of the images with you all the time. As each one is effectivly a 2500px long edge JPEG at reasonable quality they do take up a lot of space, and you still have the normal previews too remember.
On a system that is being used as a desktop, where you have the drives sitting there anyway I don't think they offer any advantage. LR only reads the actual RAW file quite rarely, when you first open it in the devlelop module for example. Or if you do a 1:1 view in the Loupe view, to build that preview. Otherwise it is reading/writing to the catalogue, and the standard previews.
If I were working using both a laptop and desktop system, where you need to take certain images with you, and work on them, say onsite with a client, that is when exporting a section of your main catalogue, with smart previews, makes sense. You then bring that back to the main catalogue on the desktop system when finished.
Another option for working away is LR mobile/web. For this to work the images have to be in collections, but not smart collections, and shared with the mobile system. LR mobile creates a smart preview which is uploaded to the Adobe LR Moblie server. You can then access it via the mobile app on your device, or from any browser on any machine you want. Any changes you make are automatically sent back to your main catalogue when you commit the edits.
You have access to all the basic edit tools in the mobile system, and you can even add new content too. It automatically adds all my smartphone images to my main catalogue, I think you can add RAW files this way too, but haven't tried it out myself. I did do a basic intro to the advantages of RAW to a couple of friends using it on a browser once.
Alan
