Re: WordPress Attachment Nightmare..
Are you referring to the actual file path? That is a non issue as most WP plugins for cloud/split level management work great with BP.
The issue is where in the database, and HOW in the database it is being stored.
If your saying I can MOVE the location from the #1 blog with a filter I havent found please let me know.
Also if I can choose which fields it uses to store them would be usefull, I have looked in WP upload and your avatar script and it seems hard coded into the users blog directory, which in all BP users case is blog #1 first.