I feel as if I am intruding on this matter and therefore I am sorry if any of my comments cause harm or irritation.
I am 5ft 7ins and stopped growing in height when I was 14.  I can only ever recall very few full blown erections due to the horror and distress they caused me but I do also recall that I once attempted to measure it following hearing my school peers talking about how big they were and I measured 4 1/2 inches.   Now consider this, there is a saying that 'if you don't use it, prepare to lose it' or something along those lines and with me, having never used my own thingy for it's ultimate designed purpose, I can safely say that I still have it  

  it still stretches to about 3 1/2 inches if I pull it hard enough and hopefully the surgeon can work with it when the time comes for my SRS.
QuoteIve heard the 3 inch is hard to pee with it.. 
I am sorry but I have to ask you something pertinent,  What length of urethra does a woman need to have a wee?    I confess that I have absolutely no idea what the thought processes are with F to M folk but I hope I do not lack empathy either.   I may be fortunate to gain a worthwhile vagina and be lucky enough to find someone to appreciate it  

 , it seems a simple matter for me but I do not know what the obstacles are with F to M's with their aquired penis, maybe I should stop here before I cause a storm of protest or lose my minimal reputation etc....
....save to say, size matters if you are a man, it is wired into the male psych, just you try to denegrate a mans tackle and expect significant dental work