I have set it manually now, but I wanted to know if using it in auto "breaks" anything.
Normally I guess people will go Max, but that isn't the answer.
If the answer is "Auto is OK", how does it choose the power level, does it look at other AP's and adjust (that's self healing?), or does it look at client connection and adjust.
Is it a constantly dynamic in realtime or change every hour, day etc.
Because they state
Note: In general, Ruckus does NOT recommend enabling this feature as it can lead to non-optimal AP power levels. With BeamFlex access points, Ruckus' general guidelines are to run access points at full power to maximize the throughput and SINR levels, thus maximizing data rates and performance.
I actually have never seen any positive effect from lower transmit power in any vendor APs. Exception may be cases, when there is just really too much APs, which is not usual situation. Even than I never seen it really improving anything.
Typically you have settings to change power for 8 db max, and this is not really a big difference when you are far from receive sensitivity threshold. Changing antenna orientation, you can get 10+ db signal level change. So receiver should handle such small level differences easy.