I've done quite a bit of testing.
- When uploading 4000px wide images, quality comes out terrible, jagged edges. Have experienced this in other situations, so I uploaded 1280 and 1936px wide originals with much better result.
- Regardless of image quality setting in Options>Image tab, the 720px wide large photos are 300K, 400K, huge; as I said, NO change with different image quality settings.
- At a ridiculously low setting of 20%, the image quality is no worse. Does this setting even work?
- The built-in Thickbox lightbox functionality is very slow, even with some 60K images I pre-sized and uploaded. Takes 4 seconds minimum to display image. A second pass through, with the images in cache is much quicker. But the delay is not much different on first pass with a 60K or 400K image.
- The built-in WordPress upload with 3 image re-sizes is a very good result but not accessible from nextGen.
- Others need to use this, so it needs to be an easy tool.