Thanks for the support! :)
Really, for keeping Cheetah going the hope is that activity correlates with price. If the volume of posts doubles, but the price of steem doubles, then the cost of running her can still be paid by the logs. If the volume doubles and the price halves, we're in trouble.
In terms of the posting limit, I've been lobbying to get rid of the 20 second comment limit, and do a better job for the bandwidth limitations. So, a low steem power noob might spam a bunch of comments rapidly, but would eat all their bandwidth and couldn't post for a while while recharging. Cheetah I can just keep with high steem power, and have enough bandwidth to do all the posting she requires.