Hmm, maybe I’m using my keyboard wrong, but I’m one of those people who more often than not use the right shift (the left being tiny due to the European style 102-key key layout). Even if I had a preference for the left shift key though, the thing would be the same: press shift, press one of the keys, press the other key with the other hand, release shift. If anything, -> is ever so slightly harder to type because the precise timing needed between the two keystrokes, whereas ~>’s both characters are on the same shift level on English layouts at least.

My problem with ~> is that on certain font sizes with certain fonts and certain hinting settings, FreeType makes the tilde look like a straight bar.