I find that the Disruptor battery lasts longer than my 18650 batteries do in my other mods. (I may be wrong, haven't tested my theory)
I use Sony VTC4's and Samsung or LG (the brown ones - forget the number)
I also find that the Disruptor could be dropped a thousand times without damaging it. (Hey, I'm clumsy)
I have two IPV mods, the IPV mini, and the IPV2X. Both are nice but the readout is so dim, hard to see it when outdoors.
I have the Koopor Mini, again dim readout, extremely dim, and it "eats" through batteries. (not a bad mod, just have plenty of spare, charged batteries)
I have the Sigelei 50 watt Version 2, and it does much better on battery life than the Koopor, but again, dim readout.
I had an Istick by Eleaf and will never own another Eleaf mod as long as I live, total junk in my opinion.
I do have the Lemo 2 by Eleaf and it's okay, needs more airflow, but It's usable.
I find that the factory coils for the Isub are right on the money as far as ohms go. (someone posted that there ohms were not what they were supposed to be)
And as far as filling the Apex, easy peasey, just fill until the liquid begins to come out of the hole opposite of the fill hole.