I was a bi-sexual before I started hormones. My initial preferences were for females, and guys as an appetizer or dessert when the mood struck me. There were only a few that I ever became intimate with, and they were more or less mentors/teachers.
After I was on full blown HRT for about 3 to 4 years, I could definitely feel a shift in my over all desires. Once I was no longer a member of the club, I viewed men, as women view them. I began to feel more and more hungry for one, and loved to be around them or near them, if they tweaked my interest. I still have great affinities for female relationships, but as close friends only.
I dated those few guys during transition, and even though they really liked me, they were not who I wanted to end up with. I never wanted to be in a lesbian relationship...although I did have one female partner for a while...she was Bi as well.
So yes, I did change preferences in a vague way...but, by not being a "hetero" I suppose my HRT influences count differently
You may interested to know, that while transitioning, my therapist warned me that I would probably end up with a man...My Core Identity test revealed I wasn't a lesbian...but, would be after SRS, a Hetero-woman with a man. He was right!
Oh! they think they are so smart... He was invited to my wedding years later, and shook my husbands hand, and congratulated him...