Yeah The Xcube Ultra was solidly constructed, although I only held it at my local store for a bit, but the GX350 is honestly not muuuuch of a small device compared to the Wismec RX300 quad battery super-mod. That's right, I've received my RX300, four new Sony VTC5A 18650s from Liionwholesale.com (they test each battery), and the official authentic Smok TFV12 Cloud Beast King subohm tank. It CANNOT be used with 12-coil "Duadary" sp? on dual battery mods. I place my equally beastly king's goblet RX300 mod on my table, Vape at 184W (odd number but I locked it at that wattage as it's perfect. The mod speaks for itself, the fire button is nice, the menu is the most basic yet, and VW mode hits are all at a standardized puff strength that makes clouds and doesn't seem too harsh. The 12-coil on the TFV4 has good flavor, no spit-back, much improved design over the TFV8 in terms of leaking, and setting off my smoke alarm. The vapor is a little warm but lower the wattage a bit and you can vape every minute consecutively without any overheating glass. The mouthpiece is a big bore long attachment, and the tip fill swings open similar to both the TFV8 and the Sense Blazer 200 tanks function. I've had some leaking do to overfilling. I never fill past that connecter from that that bottle neck top of the tank that screws into the coil and never fill without closing off the air hole. Keep upright and let sit until bubbles appear and have dissipated. I'd day 35-40 mins before you beging vaping slowly from lower wattages up to your sweet spot or else you run the chance of burning out the coil within the day. Don't forget to lock your resistance. I don't care if it's rated to do 350 maximum watts because that seems like it would fry the cotton. I use 80% VG 3mg nicotine vanilla cupcake eliquid. I've yet to reach 50% battery life and each of the cells are evenly distributing the load. I use a new model LUC V4 4-bay charger with 1.0A charging of 4 batteries, I believe, which I only tried when I first recieved that batteries at about 60% charge from the factory each, give or take. They're boxed, official, and the VPC code app will let you snap a pic of the battery code and sent you to the Sony Chem website. 25+ amps/ 2,500mAH x 4 cells in that AMAZING powerful Wismec RX300 computer chip. It makes all my tanks produce more vapor, I guess it's the automatic puff strength setting. The tank doesn't leak unless you don't inhale the without firing to clear the holes after filling and lower the fill capacity a notch before closing the airholes and putting it away. I am surprised how well I can managed the tank's eliquid and "leak-proof" design isn't the best I've used but it's not anyway as problematic as the TFV8. I bought my RX300 in Silver/Leather ($50.99) along with the tank ($44.99 [it's sold out everywhere else I trust to purchase from. Make sure you buy the tank from a good site. The price was worth the quality guarantee]) $96 plus $26 for a set of four new Sony VTC5A (they may be just under 2,600mAH but they're much more powerful with a Mooch tested SOLID 25 conintious amperage output minimum) so don't go for the 3,000mAH VTC6s because they're barely any longer lasting and a pathetic 20 amps. I know in a quad 18650 mod such as the RX300, you can have plenty of power, but don't use HG2s, if you insist on 3,000mAH get the VTC6s from Liionwholesale.com and it's tested and definitely an authentic battery you'll reveice. So about 133 bucks after shipping from Vaperoyalty.com and the Liionwholesale.com fast shipping price. Liionwholesale's regular shipping method takes forever because I'm located in LI, NY near in the middle of the island. I believe many sites are from across the country. Anyway I couldn't be happier and the GX350 my friend has is as heavy although it's slightly more compact size is coming at the expense of a higher price than the RX300 and plasticky/cheap and/or thin pieces of metal with rattling insides. Not worth it. ANY mod with more than 2 batteries is going to be a big boy. The leather vs the carbon fiber my friend has is great to grib the mod. It's a box but I compared it to the RX200S and it's a square version with one battery added to the overall size. Great battery hatch, no rattle, and a possible 350W firmware update like the RX200 updated to 250W. It's not been mentioned by Wismec by they hinted at it with the updating feature and the wording used on the official side showcasing the mod at Wismec.com. I think the internal charging at 1.5A requires a $7.99 1.5A special adapter sold separately so I charge a little more slowly and safely on my LUC V4. It's rare to get a 1A 4-battery charge from anything so I'm happy. Definitely consider the RX300 OR if you prefer the Smok GX350, I suggest 4 battery mods over the Marshall G320. Voltage and amperage pull is no problem and I can finally but my 30-32 amp LG HB6s away. TFV12, is it's authentic, is the king regardless of recent competitors. The REUX tank I have with the more vapor producing Dual coil is high watt vs. the Ceramic or triple coil. I enjoy that as well and can be less carefull filling, and tilting that tank. But the 12-coil pre-installed in the TFV12 Cloud Beast King is great, but I want to get the V12-T6 sextuple coil for the new tank and save liquid as well as enjoy cooler vaping, hopefully less waiting between hits. Get either the GX350 mod alone (black/red) available without the tank kit for $55.99 at Vaperoyalty.com or the Wismec Reuleaux RX300 available everywhere. Enjoy.