Interesting they have opted to do that, I'm a fan of nic salts but I mostly use them for MTL for that quick nic fix, I tend to use 20mg but I went down to 10mg for a spell and didn't enjoy it as there was little throat hit, now and then I take a direct lung hit with the 20mg which gives quite a kick.
My suspicions of using 3mg in a shortfill for DL is you won't feel the throat hit that you do with freebase but the nicotine will get into your system quicker.
That said, using nic salts in a 70/30 shortfill is something I'm keen to try out on my next purchase.