This is a summary of testing Haiku on a HP G72-b43WM 64-bit notebook for fun:
Haiku cannot run the GUI Network settings pane because it crashes (uh-oh!) but it did recognize the screen (much more than I can say for Solaris, and Linux distros that were made for 32-bit.) Plus, the notebook’s keyboard and mouse worked right out of the box! I might add booting was a little slower by about a minute, but everything worked!
So, if you were to ask me how Haiku did on 64-bit as an i386 version as a nightly, it did really well! I don’t really think Haiku needs an architecture port!