Well - speed isn´t necessarily a big problem for indoor. We use to have fun flying speedflying with wings that flyes much faster than this one will do.
With a speed of ~5m/s it will take 24sek to fly a round - thats no problem.

And if a 12ft Cub can fly indoor, a 9ft can too

[link]http://www.youtube.com/watch?v=AQMjG05HqJw&feature=related[/link]