I have a 510 and i also have a fifty one. The fifty one is so simple can just drip some liquid into the old cartomizer and smoke away. The 510 is great when its not flooded,dry or has fibers on the atomizer. Just seems like a real chore to keep it going without the burnt taste or flooding it out. When it works it works great plenty of vap and good throat hit. The fifty one works great aslo great vap and throat hit, sometimes get just a bit to much liquid and have to blow some out but not near the hassle of the 510. I have tried the blue foam mod (in fact using it now) also tried it with the straw and blue foam sitting on top.So ill use the fifty one as my main. Just my 2 cents worth ..