I beg to differ my friend. They are made by a Chinese company and as so there have been some cases of less than perfect machine work, bad threads were a case of suppliers sending incorrect screws and it was corrected for free as was any other problems. For a Chinese company I've actually never seen a company back their products like Yiloong.
As far as being difficult, it's a simple dual coil build, it's about as easy as building 2 kayfun's... Wicking is a bit different not necessarily trickier but I've never failed to walk anyone thru the process. If your not getting way more vapor and better or at least equal to that of a kf, frankly, your doing something wrong, ... I'd be glad to help, go to the fogger v4 thread.
As far as the orchid vs Fv4, glass v plastic threaded tank, capacity : what's the orchid hold like 3mls, common. I've spoken trio lots of people with both, if it was better I'd have one, I have 5 Fv4's. None leak... Ever. If it does your wick is too short or thin.