There are a few instances when having the original version of the file is advantageous. For example, if you’re trying to export a full resolution version of an image, or trying to edit with a third party tool, having the original might be necessary. If you’re zooming in to close detail on an image and wanting to see certain how editing might affect the sharpness, for example, you might want the original file. Everything else really works just the same with a preview as it would with an original - general editing, face recognition, etc.
As Previews also load much faster and take considerable less space, your setup is ideal. You can always request Originals on the fly (select the images for which you want originals and right click - or action menu on your iPad - and tap Download Originals). As long as your device can see another device that has the originals available - like a vault - it will bring just those originals over. Periodically, you can use the Clean Cache button under Devices in your dashboard to clean up Originals that are not needed in that device.
You can also sync Originals at the Folder level rather than the device level. Example: you have a new folder of photos from a recent trip, and want to take your laptop to the coffee shop and work just on those photos. You can ask Mylio to download Originals of just that folder to your laptop. For more info on how to do this, check out this support article under “Tap to Sync”: Setting Custom Device Sync Policies - Mylio Support