Lol, seriously. You had been fooled. There's nothing radical in those H-scenes. Also if you don't like them you can skip those scenes quite easily. And I still don't get why you're so against playing HF.
As Cherry Lover states simply knowing the spoilers wouldn't really tell much about the story. Indeed, without spoiling yourself HF may have greater impact but I can tell you it will have grand effect even by knowing all those plot twists and secrets. And no, it's not solely about Sakura as UBW isn't about just Rin either. To be precise you will know about Rin quite a lot after playing HF. Other than that you get:
-Illya's background and more insight to her character.
-More dissection on Shirou's ideal.
-Kotomine Kirei's true face and his motivations for about everything.
-The truth about the Holy Grail War
-plot twists and an epic finale with incredible battle.
Just made this list for merrymaking.
Anyways, even if you would hate Sakura with passion I think HF worth playing through. It simply answers many of the unanswered questions and can be viewed as the "conclusion" of the game. Although I am sure HF isn't for weak hearts as it plays with your emotions quite much, especially if you care about either of the mentioned(Shirou, Sakura, Illya or well even Kotomine). Also it brings up many moral questions like the infamous Player Punch at the finale you probably already know of.