Disc Brake swap-A body Rotors

I guess this would be an option for me, and possibly others that have swapped to 4 1/2" lug disc's in front, and stuck with 4" lug axle 8 3/4 rear. I have read that these were discouraged but i wonder if todays day and age manufacturing of these would make them O.K. to use for a street driver. They do say SEMA approved.

http://http://www.partzfinder.com/Wheel_Adapters_5_on_4_TO_5_on_4_1_2_p/pfp-1114.htm