While defending the 510, and I agree it's a good system, let's keep in mind that it could stand some improvement. Obvious #1 is battery life. What else?
If you're going to make a system where performance relies on
alignment of parts, then make it so those parts can't be assembled out of alignment. Mechanical engineers, and even people without such credentials, have known this for many years. Use a keyway, an oblate mating point, or something.
I shouldn't have to score my cart with a hot pin to make it fit tight. The manufacturing processes to make things to better tolerances than this have been around for years. Yeah I know, it's China, and it's cheap, but this is a solved problem in hundreds of industries.
Leakage. I fill carts at night and cap them. The next day when I use them, there's various quanties of juice on the flats, and sometime spilled in my case. And yes, I'm careful to not overfill -- learned that lesson.
If the 510 were truly great, we wouldn't have pages and pages of mods. Granted, there's likely not a single filler or ZFM that'll work with any and all juice, and that's something that's just part of using a 510. I plan on trying out dripping pretty soon, because I'm already tired of dealing with carts.
Different strokes, or for you Brits, horses for courses.
Can hardly wait for my eGo XL to show up.