That's a question that'll probably get many different answers, as no one has ever published any hard performance data running a modified factory suframe and the aftermarket versions back to back. Until that happens, all you can do is talk with the manufacturers and individuals that are running them.
I'm personally going to push my stock subframe to the limit by using DSE upper and lower control arms with delrin bushings, their true coil-over conversion, the 600 steering box, 1-1/8" sway bar and fully welding all of the seams on the subframe.
Good luck
