Nic salt will definitely affect the flavour, because it doesn’t have much of the nicotine flavour you get with the regular stuff or as much throat hit or harshness. Also if you are letting it sit after mixing it (steeping) my experience with salt nic is that it definitely doesn’t work the same as regular nic. It changes colour noticeably less and takes longer for flavour to develop. I have 2 bottles of the same liquid here mixed on Saturday one with salt and one regular and they look very different from each other.
Personally i would think at 3mg salt nic might be a bit pointless, especially if it costs more. The advantage of it is smoothness at high strengths. But I might be wrong, maybe here is a reason to do this that I don’t know about.