Because of the anime entering Alka I replayed the game for the first time in 6 years, this time Reflection Blue. Overall I'd say just playing Reflection Blue gives you 100% of the experience, but playing the regular version first and then RB gives you 120%. The difference between the original ending and the new one isn't that many lines, like maybe 10-15 minutes, but it really has a huge impact on how it leaves you feeling. I'd say the original is bittersweet but hopeful, while the new one is a guaranteed happy ending. That's why I hope the anime goes with the original ending, playing through the entire game again, especially Alka, after having done Pocket just makes what happens so much more heartbreaking, and makes the ending of Reflection Blue have double the impact so that's a good thing for people who want to play the game after watching the anime. I really hope they keep the ending song with the original lyrics instead of the new one, this probably won't be an issue if you don't understand Japanese, but personally I like the original lyrics way more, even if the new ones fit the story better.
Shiki's route is pretty good so if she ends up not being in the anime that's just another reason to play the game for animeonlies.
Also get fucked Tenzen my little girl and me kicked your ass.