I've made a TRANSPORT analysis of the possible changes in Q2/3 noted earlier. I started from the standard APEX tune. Then changed Q2 and Q3 by 0.02% (i.e. I took the standard field in each magnet and multiplied it by 1.0002) and reran TRANSPORT to see how the 1st order matrix changed. Where the matrix elements were finite they changed at the 1E-04 level. For elements that were 0 to start with they changed on the order of 0.0001. Full details are in the attached .xlsx file.