I'm quite sure that this is not good: since MC2 can produce a signal in WFS1 and WFS2, it cannot be removed in this way from the actuation without introducing a significant cross-coupling between the MC_TRANS and WFS loops.

Really need loop TFs measured and compared with the model.

The WFS noise model will also show that we need to have a much lower UGF in the MCT loop since that sensor is just a DC QPD: it can never have as good of a sensing noise as a good WFS. In the current case with no Whitening, this is even more so.