Sorry haven't been checking the site in a while. Glad to hear that you were able to gain root and install the new rom with help from others.
As stated above, in order to get the 2.15... radio you need to do the Unrevoked forever however once you go s-off you can not turn it back on, at least not yet.
I haven't noticed much improvement between any of the radios except the 720p recording, which you can do with just the OTA update. Of coarse you need to go back to stock in order to apply it.
If everything is working for you and you are happy with it, I say stay with it. If you like to fiddle with your DINC (like most men do) install forever and apply the new radio.
well I want to install a new radio to see if it fixes my GPS which is the only thing thats not working. I tried to install forever but it wont work? I downlaoded the file. Put in root of SD card, put my phone in recovery, selected forever as a zip from my sd card, applied it, rebooted my phone and it still shows the S-ON. What did I do wrong?