If you assumed an RSS feed that is fixed not to exceed 10mb, I think you would be in the ballpark for daily transmit size. I will see if these groups have an interest.

I had read in some older posts that there was a way or you were looking at implementing a method of users being able to place content to be transmitted, did anything ever come of that?

Lastly I am an Amateur Radio Operator and while I can appreciate the APRS functionality, have you given thought to integrating any other Amateur Radio functionality?