For some reason I just can't get on board with harness bars. Seems like the wrong way to do it although they mount up to the OEM points.
I am of the same mindset. While a harness bar does allow you use shoulder harnesses, I would hate to see what would happen if you were actually in a rollover accident with it. The roof could potentially cave in on you and the harnesses won't allow your body to move out of the way.
So is your sub belt bar going to have the belts running in front of the seat? If so, this will do very little in stopping you from submarining during an accident.
I don't want to sound preachy, but in the end all of us must decide how much risk we are willing to accept with our safety equipment while on track. If you are comfortable with this setup and it works for you then that's great. Personally, I won't run harnesses without a roll bar and fixed back seats.
Oh and your car is awesome :beer: