I ran a 28g core with 32g outer in my subtank for a while. I found it to perform magically. 5 wraps on a 2.0mm brought me to 1ohm.I'm guessing it might not truly perform in a RTA in that case..
Flavour and vapor production were stellar. It just needed a bit more power than usual 1 ohm builds. I ran it comfortably at 28 watts.
If I wasn't running nickel on my subtank I would probably have another one of these in it