>I already have X CACHE, is there any issues with it?
xcache is php opcode cache, not relate with litespeed page cache at all.
>Btw, that works only for guest caching? What about members after they logged-in? Are they cached as well?
you can try to cache all pages including logged-in user, as long as logged-in user has no objection. however, when a user want to read his private messages, but read other user's private message since it's cached? when he want to edit his profile, but see other's profile ? etc.