Besides an update to the existing OpenSSH package, it would be very nice if the MSYS package would come with the HPN patches  applied by default until they are eventually accepted upstream. From the HPN FAQ:
Q: If this HPN-SSH is so great why isn't it in the OpenSSH code base?
A: The HPN-SSH patch has been made available to the OpenSSH development team and I hope it will be incorporated (in either its current or some other form) in the near future. However, the team has other priorities and I'm perfectly able to maintain this patch until they can free up some time. Quite a number of organization are using HPN-SSH though including NASA, Sun Microsystems, HP, financial companies, research organizations, supercomputing centers, security concerns, and software developers.