Haven't used them.
My concern with renting a finish throat reamer would be it's condition. They are extremely hard steel and prone to the cutting flutes chipping if not handled with care.
I bit the bullet and purchased Manson throat reamers for .44 (mag) and .45 Colt.
I seem to acquire quite a few S&W's and a few Rugers in these calibers--and every one of them have had varying degrees of constriction, or too tight throats.
While this was less a problem with jacketed bullet accuracy, it caused cast bullet accuracy to be far less than ideal in my experience.