[p2k]

Unless you live in a rural area, I would personally leave it on EVRC.

Although some argue that 13k sounds better, it has worse error correction. Therefore you have a higher likelyhood of getting garbled sound. And within a busy city, interference can occur quite often.

The tower need to support 13k, and not all of them do, so you need to check your location. This may mean that although you have signal at your currently location you may not be able to dial out because the tower doesnt support it. This alone would make me worry, if you had an emergency and you couldnt call 911 or something.

13k uses more bandwidth than EVRC (8k) so if your at in a busy cell grid, you may not be able to establish a connection to the site.