My first Provari is the full size. I got a chrome extension cap back when Provape was still selling them. I use it in both default and extended form. Fresh batteries in the morning. The 18450 begins blinking around 7 pm, the 18650 starts around 10 pm. For most situations the Provari in extended form best fits my large size hands, and the fire button placement is nearly spot on. In extended form it can get a little wearisome and heavy to carry-out-and-about, and is not quite as pocket-worthy. (Just my opinion)
I had always wanted a Mini to use mostly for on-the-go situations, so I gifted myself one for my one year smoke-free anniversary. It is lighter in the hand and quite pocket-worthy, and in default form can be quite stealthy in one's hand. The button placement is not as convenient as with the larger Provari due to the Mini's shorter length, but I've only had it for three weeks so I'm sure I will adapt quickly and natural finger placement will automatically occur at some point. I only use it in its default mode, because that is why I bought it. I have tried the chrome extension cap from the original Provari on my new black Mini. It fits perfectly and looks quite nice. The regular Provari sees more at home use now, and the Mini gets to see the world.
Which one to get
first, I would say consider what situation you will use it the most. If when out you want a great vape with portability, more lightweight, and more pocketable, get the Mini and just carry a couple of spare batteries with you.
If this is going to be your ALL day device, both home and away, I suggest the Provari with battery extension to use the 18650 battery for all day use.
My Mini and Provari with battery ext

Mini
regular Provari with battery extension