Thanks for the plugin work!
One issue I found when inserting a number of images is that the image class selectors were being duplicated for each image inserted, so we would get results that included image class values looking like the following:
first image: "aligncenter size-large wp-image-6397"
second image: "aligncenter size-large aligncenter size-large wp-image-6398"
third image: "aligncenter size-large aligncenter size-large aligncenter size-large wp-image-6400"
To fix this, I modified line 120 of includes/attachments.php as follows:
$imageclass .= ' align' . $align;
$imageclass = ' align' . $align;
seems to work fine so thought I'd communicate it back.