I have the old HO racing bars which were built by Suspension Techniques. I have also used their bars on a Monte Carlo and 2 Mustangs. Nice stuff. A hollow bar is nice for all out racing, but on a street car you are spending money for the sake of spending money. I'd sooner use junk yard TA bars with new bushings.
I can break a steel ball in a rubber room.
Material makes a difference. I believe the Hothckis bars are make from carbon steel not cold rolled. The bars are stiffer and won't flex like some others. Send 79T/Aman and e-mail, He's an authority on suspension pieces.