Hi @jamieburchell,
We do save the first image in the listing as the normal WP featured image which is stored in the media library, however all other images are stored in our custom tables. The reason we do this is so GD can scale to millions of listings. Each image stored the normal way has about 20 database rows, where as we have one.. imagine a site even with 5,000 listings, and 10 pics each, that could be over a million database rows. The vast majority of listings are usually added by users who don’t have access to the media library also.
let me know if anything is not clear:)
Thanks,
Stiofan