Having been pretty much every colour there is [and sometimes several colours at the one time] and having had everything done to my hair [from dreads, to shaving it all off, its currently red and half way down to my back] I can say I never noticed a major difference in peoples treatment. I mostly found it was how I felt about my appearance that effected how people treated me. Had a few bad hair style choices and I'm pretty sure it came across to people. Not ever cut, style or colour suits every face/body type so it sometimes its trail and error.
Kazobel - don't take this the wrong way but you say your pre-op and living as a female but how passing are you/confident with your appearance? I've a post-op friend who lost some weight but found that the weight lost from her face made her look more male and it shattered her confidence for a while.
The times you felt people had a good reaction to you do you think it might have been down to being more confident in your overall appearance rather then just the hair colour?