First, thank you for the write up and radio links and contribution to all of this.
Now for my question: Wouldn't fastboot be easier and safer?
1 - Copy the .img to your /sdk/tools folder (or whatever folder depending on computer OS). Verify MD5.
2 - Boot into bootloader (Vol Down + Pwr).
3 - Navigate to Fastboot (Vol down to Fastboot and press Pwr). Make sure your phone says Fastboot USB.
4 - Open command promt (or terminal depending on OS)in folder you put file.
5 - Type:
fastboot flash radio xxxx.img
xxxx is radio name.
I find this faster and safer. I find SDCards can corrupt the file easier than anything else therefore leaving the file on your computer to flash from is one less transfer and possible issue. As we all know, the 2 things that have the greatest chance of bricking a device are your Radio and Bootloader images.
Just my .02
Nexus 5 - PurityROM
Nexus 10 - PurityROM
Nexus 4 - My Son is using it running PurityROM
TMO SGSIII - CM10.1
HTC One S - Sold
TMO SGSII - Sold
Sensation 4G - Sold
MT4G - Got a new one! Stock 2.3.5 with root.
Nexus One - CM9!
Vibrant - Let in-law use it. Just wasn't cutting it for me.
MyTouch3G Slide - Returned
MyTouch 3G - Sold
G1 - Sold