I used to use iThemes security, and then with the changeover it was just not delivering a stable solution. I changed to the paid version of Wordfence and have never looked back.
Yes ... you need solid backups before changing anything.
Changeover notes - I found Better WP Security/iThemes had made changes to my htaccess files and a few other things that were not removed on uninstalling the old plugin, and I needed to go in and manually delete their traces. (There's quite a few Google articles and a few forum posts out there on how to manually remove all traces). Hopefully iThemes have improved in removing all traces of their plugins over recent weeks.
I also had caching traces left behind from other caching plugins that interferred with Falcon. Once I ferreted them out, Falcon has been brilliant.
Bits that are a major improvement - if caching is not an issue for you, geoblocking is great if you are getting hammered from particular geographic locations. I also am a massive fan of the latest changes to autoblock on particular names being entered admin, administration etc. This was superb over the weekend for my sites.