Easy way to show the benefits of refinement.... place your device (no atty attached) in the fridge for 30 minutes. Place atty there also. Remove from fridge and immediately attach atty and lock in resistance.....(note ohm's resistance) and vape...... let set at room temperature for 30 minutes....(note ohm's resistance) and vape again....
Or alternatively, lock your resistance on the SXM while at room temperature. Throw that and your DNA40 device in the fridge, come back after an hour and then vape on them while cold.
Both approaches have weaknesses that can be exploited by a user to operate the mod in an undesirable way, but only with the refinement approach has there been a lot of complaints. The problem with refinement is that it only changes the room temperature resistance, which means the vape can end up hotter than when the user first set it up they way he or she liked it. Meanwhile, if the resistance is locked, the vaping experience remains consistent.
Put another way, the refinement method, under certain assumptions, might give more accurate temperature estimation, but it lacks stability from the user perspective and also is substantially undermined when those assumptions are not true. Locking the resistance under the wrong conditions can lead to less accurate temperature estimation, but a knowledgable user can easily avoid such conditions. More importantly, even if room temperature resistance is slightly off, the lock resistance method remains consistently stable from the user perspective and thus will not affect user satisfaction.