Yeah, definitely.
Although, it doesn't take much for Sakura to be "swept off her feet" by Shirou....
Well, you've already moved away from all three routes simply by changing the servant summoned. Saber is important to Fate and UBW, and there's no way Ken would allow a HF-like story to proceed as HF did. He'd deal with Zouken and save Sakura way before it got to the point of her turning Dark.I think, however, I'm gonna have to not follow one particular route. Can't do Fate for the blindingly obvious reason that the main love interest is replaced by--well--Kenshirou. UBW might've worked, but it'd require Illya's death in order to complete, which I'm against as it'd negate one of the future awesome scenes I'm thinking up. As for HF... naw. Dark Sakura would, well, to be frank, too broken.
For this reason, I think I'm gonna make my own route. As heretical and insane as it sounds.