Default Question about flashing NB4 modem to SGH-M919n

I have a Gs4 with Metro (I know TMO and Metro are basically the same.) and I want to try the NB4 modem but I can't find anything on the pros and cons when flashing from MK5. I can't find much of anything about the switch on XDA or any other forum. My question is, will switching to NB4 hurt anything? If not, can someone give me a link on the best way to flash the file.

Thanks in advance

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