Hey there! Give me a moment and ill try and answer each concern ~
I plan to have just as much content in each LiB update as in each SI update. The plan is for V.01 (the first public release) to have about 2 hours of content. Along with easter eggs and special scenes to unlock just for fun (they dont affect the story and arent canon)
The story WILL be more mature and grounded, definitely no plans for magic or anything, but I dont plan for it to be extremely slow moving. Ill have a bit of sexual content with each update, inluding the first one. No drip feeding over the course of months. Even if the sexual content isnt canon, e.g in V.01 you obviously wont already be having sex with the girls, but there will be plenty of scenes that will be fun enough to get your rocks off to.
The game will still be harem, and similiar to SI I plan to have character specific endings if you choose to pursue one girl instead. There will be no other guys, no NTR, no sharing, anything like that. Ever. This also stays true for the female route (you can choose your MC gender, not sure if youve seen that yet). You will never have to share your girls and youll never experience a game over or anything. The only 'scenes' youll miss is if youre playing the Male MC, youll of course need to play the Female MC to get the female scenes, and vice versa. The only possible negative consequences (not yet 100% on these yet) will be if on optional dates/events you pick negative dialogue choices, the event may end, and youll just have to wait an in game day to try again. But no permanent game overs or anything.
I am glad you like my Daz work, and hope that this helps alleviate some of your concerns.