I choose not to speak masculinely. If I were to de-transition, for whatever reason, I'm fairly confident that I would still use my female voice... because listening to my male voice really bothers me. I hate hearing it a lot... it made me cringe when I used it as a 'guy'.
I just refuse to do it any more, regardless of the situation. I don't want to be afraid of speaking because of how much I hate my voice.
I can still do voice impersonations, though. Not, like... Darth Vader, Optimus Prime, or Jean-Luc Picard... but I can still do some strange ones.
If you feel comfortable with using your male voice and presenting female, then by all means do so. It will probably take away from your quality of life, because people won't treat you as kindly (on average), but speaking with a voice that you are comfortable using is important for one's sanity.