Mark,
Sorry for the delay. We've been trying to recreate and understand the issues, but actually ran into some silliness with Amazon S3. We think we know what needs to change though, if you're interested in trying. It should, hopefully, be a simple fix. If you're up for it, edit the /modules/mod_sclogin/helper.php file. Around line 220, you'll see:
$jsUser = & CFactory::getUser($user->id);
$avatarURL = $jsUser->get('_avatar');
Update that last line to:
$avatarURL = $jsUser->getThumbAvatar();
Hopefully, that's all there is to it. If not, or you run into other issues, just let me know.
Thanks,
Alex