I may be doing something wrong. After switching back to S3 uploads, custom avatars are broken.
The image file uploads correctly and appears in the S3 bucket but the image tag is:
<img alt="" width="120" height="120" src="/user_avatar/[forum.hostname]/vocino/120/5155.png" class="avatar">
This is on v1.3.0.beta10 +22.
Image uploads seem to be displaying correctly when uploading an image in a post.