Just saying that from watching the “Unlimited Blade Works” movie, that aspect of the story made a hell of a lot more sense then it did in the eroge… I’m pretty sure the movie was staying true to the all ages version, but I personally liked that fact.
If you wanted to establish a sexual relationship between the Rin and Shirou, one could have done it easily, as it was pretty obvious that they felt something towards one another in both the virtual novel and the movie. So it wouldn’t have been that weird that they’d hook up without the excuse of “sexual mana!” but plain “Oh Shirou, I may not be able to see you again after this, lets shag!” instead. (well forgive me, I’m not that experienced in writing novels ;))
There was some eye candy in it though, so it wasn’t all bad… but it definitely took a while to get rid of the initiate giggles.