One cautionary note, while this all works really well - and I've even now tweaked our admin screens, variants and detailed images to use this with lytebox as well cause we love it so much - at some point uploading a too large image will break things.
We had a client upload a 1.8mb, 300dpi, 1980x3000 jpeg and the entire category that the product was in went missing - you click the category and you get a blank screen. Downsized the image and everything went fine (Images on the file system)
I must admit I haven't checked further yet to see if it was Xcart, the mod or something else that crashed it, but I've got my eye on it now