Completely compatible.
I've several of the PC (plastic)
tank iSubs and usually have one running (right now in fact).
An upside is the addition of factory coils besides the original 0.5 ohm.
Haven't tried the 2.0, but I've had the 0.2 up to 50 watts (surprised me actually, I wouldn't go higher though).
The downside is there's no rebuildable deck for the iSubs or the new APEX tank (yet?). Or TC coils.
So while it's possible to recoil an iSub head, it's a tad finicky. So, no TC wire heads otherwise (Ni & Ti).
I really like my iSubs (and my D2) but if TC or a RBA deck are important right away, perhaps another tank to start or in addition.
If you use or plan to use higher ohm non-TC coils, say over 1.5 ish, and prefer low watts, there is an issue with the D2. It lacks the circuitry to "step down" the voltage below the battery voltage while in Power Mode (watts).
The workaround is simple though... use the non-TC coil in Ni (nickel) mode, set the temp to max and treat "Joules" as "Watts". They're the same in this application. Easy as cake... piece o' pie.
