The image settings I mentioned (and where id242 and JAISP clarified) are all in the 7.5 code; nothing was changed in v7.6.0 for gallery settings, just the way the gallery items are presented to the user.
Note that when a user uploads a 20mb file, and IM changes the image quality and image size, it'll have a far different size on the server (hence my suggestion to play with the upload settings on your site with large images to find a combination that works for your community).
IM uses the same behavior as the default GD setting, it's just a higher quality end product; originals are not saved, just the full/medium and thumbnail images.
And yeah, we're both pretty bummed today, being home from Summer Camp 3 nights early; unfortunately, just as we got him over being homesick (he missed his Nana and his sister) he got sick into the lake (we had him sitting down fishing with another scout who had homesickness last summer at camp).
