Advantages: Free! Allows anonymous uploading (i.e. you don't need to create an account). Files up to 12Mb in size. Disadvantages: Full size images apparently don't display 'inline', but require you to follow a link. The link address needs to be slightly edited to work in this forum, as follows:
#55448, "RE: Test thread for third-party image hosts." In response to Reply # 8
Your QM2 photo looks good!
Re. the unavailable images at imgur, this is something I noticed once or twice on other sites in the past. A placeholder image was temporarily displayed when the imgur server was overloaded. As I mentioned, it is not something that happens often.
A pinned message is a good idea, once we've decided which host works the best. So far imgur.com looks pretty good.
The forum attachment size limit is unfortunately something I have no control over. I too hope that someone will look into it soon.