Hmm.. how is this supposed to work? The typical use case is

    picks = mne.fiff.pick_types(raw.info, meg=True, exclude='bads')
    epochs = mne.Epochs(raw,.., picks=picks)

If you want to keep the reference channels, CTF users would always have to say `ref_meg=True` in pick types, which I don't think should be necessary. The other way would be modify to `Epochs` to always include ref channels, even if they are not in `picks`, but I don't think that would be a good solution since it a) gives the same potential problems that @dengemann mentioned (visualization) and b) makes it impossible to not include the ref channels. Also, I check the viz code with the SPM example, and everything is working as it should (it only shows MEG & EEG channels, ref channels are excluded).