I recently went back to at&t's latest rom titled "CINGULAR_WWE_3.62.502.3_6275_1.54.07.00" which I downloaded from the htc site, and I think is still available for download here


Click on the forum "thread" link. I had the hardspl settings just like you have and after loading this rom, it has updated my radio as well, but I still have the same ipl and spl. The phone is still unlocked to any carrier and supercid. Hope that helps