Yes, the radio can be flashed alone. That is what I did a couple of weeks back. I used the SD flashing method to do it, wherein you load your fat32/1024 formatted card with the image, named TITAIMG.nbh and then enter bootloader mode. It did take me a couple of tries, though. Although I remembered that the microSD card was supposed to be a non-HD (less than 2GB in size) variety, the bootloader still wouldn't cooperate until I renamed the ROM radio image precisely as named above (including type-case).
As I recall, no data was lossed performing the image.