Most of the roleplays I'm in fluctuate wildly, and that is part of the problem. My first one started with... 13, dropped to six, skyrocketed to 20, and then died when our GM vanished. The second one dove in with 23, and my character was quickly lost. The one after that had five, and I can blame its failure on one specific person (this was on another site, btw). So, varying between 5-20. I've found as soon as there are more than about eight people, not including the GM, things start falling apart quickly. That's why I'm scared. Now, I haven't had as much experience with group roleplaying on Iwaku, so maybe I'm jumping to conclusions, but the couple that I've tried here seem to have the same general problems. People flood to join, characters interact quickly, chaotically and randomly, and then a good portion of the members vanish and things come to a stand still. The larger the numbers, the quicker that comes to be.
I won't deny, when I was reading Mass, I was thinking... everyone on the site
So 50+ people at a time. But with a well-practiced GM and a reliable member base, I could see it going well. I just haven't
personally experienced it. And now I'm somewhat jaded.
But exploring a world is one of my favorite passions, and if it will be a controlled experience, rather than a free-for-all, I would love to be one of those reliable members I mentioned before.