Sorry to make you wait. I was on vacation and I guess all the other guys are busy with other things. (Especially, I haven't seen @Slavik around recently.)
OpenLiteSpeed isn't a drop in replacement for Apache the way LiteSpeed Web Server Enterprise is. You can definitely do most things you would do with Apache and it's definitely safe, but you have to set up configurations yourself. (Enterprise automatically reads and runs off of Apache configs.)
After that, though, you'll have to set up each domain in OpenLiteSpeed's configs. You'll need listeners (you might have them listen on a different port so you can still serve your sites with Apache while you're trying things out), virtual hosts, and to configure PHP. Then you'll have to copy .htaccess rules into the vhosts and set up other parts of the vhosts that are specific to them. On our installation page, we have a few guides for setting up popular web applications with LSWS. Let us know if there's a guide you'd like to see. I'm not sure when we'll have time for it, but we do have a list of guides to create.