I think the 80 would be a great upgrade over the istick. Everyone above you, however, is spot on in my experience too. I would suggest getting both a removable single battery mod like the 80 and almost immediately beginning research on a dual removable battery mod capable of 100 watts.
As you're lusting for more clouds, exactly as hans said above, check out the tfv4, arctic, freemax starre, or zephyrus (there's plenty more too) if you want to keep purchasing factory built coils, if you would rather spend that money on gear start looking into rebuilding and move into rebuildable tanks and drippers, and building your own coils. That's where the ideal vapor can be found since you can tailor your builds to suit your wants.
Cheap dual battery mods would be the istick 100 ($34) or the koopor 200 ($50), and there are dozens more just above the $50 range to $75.
I don't own the smok 80 but I tried one out in a shop and hated the bar. For the single battery mods I like the koopor by smok and the ipv d2. Sigelei 75's can be found cheap too, picked mine up for $35.