Re: 4 images Gallery
If your images have comments, ratings, description, categories, etc, I would highly recommend importing, even if it takes some time for someone to offer an import script.
Can't speak for Brian, but I believe he would make that importer being 4images such a popular script. But being Brian such a busy guy, that might take a while, so you should wait for his answer.
On the other hand, if you don't have nothing like that, you could just upload all photos by ftp and bulk post them.