My wife and I been using the subtank mini with the RBA now for 2 years and have no intentions of looking for something better. I can't say about the factory coils since they are still unused, the ones I did use I pulled the guts out and set my own build into and in a pinch they are OK but not as regular use. I found bellcaps, orings and bases all in fasttech(not the styled or clone either) so I have enough parts to last a long time. The subtank offers a wide range of build options, enough to suit my needs. I haven't had any problems with our subtanks, got building and setting the wick down to a science, can have them sit for days on a stand without leaking or lay them down on a table overnight and nothing. IMO its the people who use the factory coil that have the most problems with the subtank and also those who had a bad experience with the portanks back when they were a issue that left a bad taste in their mouth...me on the other hand had no problems with protanks or subtanks cause I made my own coils also wicked with rayon. I will say inconsistent factory coils are the bottom line to a lot of problematic attys, also paying 3-8 bucks each for a coil head that could last for seconds also is a major turnoff in deciding what atty one should buy.