ray156,
Taking out a DHS (dynamic hip screw) should not require that long of an incision, as the side plate on the system has usually only around 6 screws. The incision would only need to be just long enough to get the side plate off. Unless you had a custom made prosthesis, that was much longer than the ones normally in the sets. But, anyways...
Taking the prosthesis out may decrease any pain you have on the lateral side (outside) of the pelvis and hip region. Such as, if you have trouble lying on that side. Or, if you have trouble with the tensor fascia lata muscle moving over the plate when you flex and extend the hip.
But, it would not help any pain you would have in the low back or in the groin region. It would also not help any pain that is coming from the hip joint itself. And, of course, it would not help the ankle or foot.
But, if you want it taken out, that is up to you. As long as you are willing to go through the procedure and the rehabilitation afterwards, it is not unreasonable to have it taken out (as long as the fracture is completely healed).
Just go into the surgery with realistic expectations.
Good luck.