They are perfect for nicotine salts and are an ideal kit for those on disposables looking for something more permanent as they work in a similar fashion with good flavour and vape production.
Have you tried or read the reviews for the original Caliburn model? As far as I am aware (although this is purely observation from having used and seen both devices) the A2 features a small window so that you can see through to the juice similar to the G2 and a lower ohm pod that is ever so slightly more powerful and flavoursome. It also features USB C and charges up pretty quickly.
Typically the A2 is priced cheaper than the original Caliburn, I like to think this is because they haven't included the USB C cable but I don't know for sure.
The only downside with the A2, which is only a downside if you shop local, is the pods can be harder to obtain as only the A2 uses the A2 pods as far as I'm aware (most Caliburn pods are cross compatible with another device)