I have used Lazyest Gallery on several sites and think it's the best way to show images without having to load them into WordPress.
I just activated the Eazyest Gallery 0.1.0-RC-4 on my test site and didn't even want to proceed because of the upgrade page. Apparently it uses a custom post type for the images? How is that easiest?
I recently went through an exhaustive search of the gallery plugins trying to find one that is responsive and does its thing with the least possible intervention. Most that fit this description override the [gallery] shortcode, which is by far the easiest.
I was using Catablog on an old site to show 400 images from a project. I had to do an extensive conversion to remove the plugin and uses a different way to display them when I wanted to mix and match those images with some new ones. They were in a custom post type and I wanted to preserve the dates and titles. It would have been so much easier if they were normal images in the database, treated differently by the plugin.
I hope you aren't going down the same path with this new plugin. It should either
1) not put the images into the database
2) use the WordPress standard image post type if it does.