I've been using a 900 mah X2 since November, I have 2 of them. I go through almost 3 mils of liquid a day and one lasts me most of the day on a charge. I use the T3 mini tank because the larger one is just too bulky for me. I love them and they are still going strong. Since my original cig-a-likes were from Halo I really wanted to stay loyal but those were worthless to me so I switched. When I learned Halo had an 808 thread battery that was similar to the X2 I decided to buy them. My husband wanted the smaller Triton (400 mah) so I got him the kit, it is a little more expensive than the X2 but it is all very nice quality and if the charger holds up it will be a one time cost so eventually the Triton will be about the same if not less in price. I also purchased a 900 & 1300 mah Triton for myself. I have only used the 1300 one day and on the original out of the box charge, it lasted one full day of heavy vaping, I am hoping for longer on the next charge. I used my T3 mini tank because I am not fond of the top coil (and larger) tank that Halo sells. It is a warmer vape and my husband prefers the warmer feel to the cooler one of a bottom coil like I use. I believe the replacement wick unit of Halo will end up less expensive than the X2 replacement coil and may last longer as well. I don't know yet....will update once he uses them more.
Honestly I believe the 2 will end up being about the same and it will end up a preference of top or bottom coil. The batteries will depend on whether or not you use the pass through or not, I don't see that as important. The Triton is much shorter at higher mah and that is nice. They are both, in my humble opinion, very good products and I am going to have a difficult time deciding which I will purchase when I need a new one!