The M9 does provide users the ability to control the initial Q value.
The Q value changes based on the number of tag responses and collisions using the algorithm specified in the Gen 2 specification.
Because the Q value changes at run time, there is no way to display the Q value.
The initial Q value can be read by reading system parameter 0x0010.
The Q value is set to 4 by default and will automatically increase or decrease based on the number of collisions and tag responses.
The Q selection algorithm is similar to Annex D of the EPCglobal Gen2 specification.
The initial Q value can be changed by writing to System Parameter 0x0010, Tag Population
For a Tag Population = 0 or 1, Q = 4 -> # slots = 16
For a Tag Population of 2 to 254, Q ~= log2(Tag Population), From the definition #slots = 2^Q
For a Tag Population of 255, Q = 9