As a viewer, I feel if the map is too small then it won't showcase the game well. TF2 has very distinct classes with very different skill sets. A larger, 5 CP, map with different points really does an amazing job of showing this.
I do agree that matches can run forever, especially best of 3's. I like the idea of a 30 minute time limit. The stalemates can be a little boring but so can a match that takes over an hour. I know they don't use unlocks but the EU seems to do really well with drawing in viewers. Just yesterday they had almost 1k viewers on twitch for a match. I'm not saying it's because of the time limit but maybe this is something to consider.