Short answer: yes.
Long answer: People tend to speak like this, but mostly because adding "therefore" is an afterthought and so interrupt the current sentence to add it. Generally for written text you want to be more formal, so it is generally preferable to minimize pauses that would prevent the normal flow of your sentence. This isn't to say you cannot have "therefore" in your sentence, but rather that having it in the middle of your sentence would tend to add two pauses when only one is necessary if you had it in the beginning.
So in the interests of reducing pauses and not being as long-winded, I would rewrite it as follows:
Method A requires difficult computation. In addition, method B can
only be applied to a bivariate case. Therefore unlike methods A and B, Method C is the most appropriate method.