I'm pretty sure the large recent signup count is due to large SP holders claiming free accounts. The data in this post appears to show that the number of comments and posts haven't really been affected by HF20, which is a little strange since it was intended to stop Spam.

I made a post that takes estimated traffic data and keyword strength for Steemit.com that shows that the traffic levels have not recovered following HF20 - but maybe that data is inaccurate:

https://steemit.com/steem/@ura-soul/low-traffic-levels-for-steemit-com-post-hard-fork-20-show-yet-more-reason-to-support-a-fresh-user-marketing-campaign