No, the difference I was explaining was only for the 16x84 series. I was just making a point that not every C version chip was one-time programmable.
The 16C57 is definitely a one-shot deal, so you can't really use it unless you're going into production and plan on selling them.
Unless you're planning on just programming it with the BS-2 firmware once, in which case the C version will be fine. Note though, that if you make any mistakes, you'll have to toss the PIC in the trash and get another one.
Unless the F version is a lot more money, you're better off using it in general.