keep in mind you need to keep a constant vigil on that center post and make sure its not out to far
Mine HAS to be out or it will short my 2.0 (but not on the Grand). I had read everything about making sure it was screwed down, but that is what blew my spring. I put in the new spring and short stop and it would have blown again had I not had the short protection. I metered it fine, it worked on my grand. Once I used the handy screwdriver that came with the A7 and screwed it out, it was fine. It vapes wonderfully now.
So clearly this is an issue that is individual to each REO and each atty. My only suggestion would be to use a short stop and figure out the right combination. As with any mechanical and atty, you just need to get the right power to the wet coil sans shorting.
As for the cost issue, my A7's work just fine. I have expensive rebuildable atties, I have cheap atties (although for tubes not the REO). As long as the
juice is hitting a hot coil vapor will be produced. How you accomplish that has nothing to do with the price, but everything to do with your wick and coil and the delivery of power. So if a cheap A7 does it well, I see no reason to pay more money for something that does the same job. My ZAP works great on my ProVari, but so does my el cheapo chobra as long as the coil is adjusted to the power.
I am sure that the higher priced atties will have less variance and higher quality control, but so far I haven't come across an A7 that has a wobbly post (knock on woodvil). It doesn't require a gasket, and is easy to rebuild so works for me!