What an interesting question! From my personal experience, being a homosexual couple would not complicate the rental process, regardless of the area or type of property development. There can be complications when trying to have two people on a tenancy agreement, but this would not be exclusive to homosexual couples. Usually, all parties that sign the tenancy agreement would need to provide a HKID/passport and proof of income to secure the apartment. That might not always be possible in this type of situation. There can also be some complications with visas as Hong Kong currently does not provide dependent visas for homosexual couples, including when the couple is married in their home country. I typically do not recommend than anyone put two names on the tenancy agreement due to legal liability of both parties to the agreement. Essentially, the actual rental process is the same for everyone, regardless of sexual orientation.
If you are questioning this from a more personal experience point of view, there can always be landlords who are not willing to rent to people because of their sexual orientation. Unfortunately, this is still a fact of life for people around the world. But, again from my experience, this topic usually does not come up in the rental process so there would be little opportunity for the landlord to know anything before commencing the lease. And, I have never had a landlord ask this question even if I knew they suspected it. As for your neighbors, I can honestly say that I have felt safer in Hong Kong than anywhere else I have lived. As long as you do not bother them, people here tend to live their own lives and let others live theirs as well.
I hope that helps and please feel free to contact me directly if you have and further questions or need more specific advice.