Email from Josef:
Chris, we need to take into account the M1 (and to a degree M2) currents and the FC currents. John Cobb's suggestion to use a relation like IF = 184 - 0.24IM seems to be a good first approach. So: if M1 is 200A we would put the FC to 136A. The above relation is for flip mode but I cannot see a good reason why we shouldn't use it as a guide for solenoid mode too. For each setting I would consider the interaction force too of course and, at this stage, we have not been above 15t.
Rogers: note IF = Focus coil current; IM = M1 current