zita-a2j and capture alignment

In my continued quest to use a pair of clock-synched Delta 1010 cards
together to record a whole live band I've recently been using zita-a2j rather
than the alsa pcm_multi approach. It is much less prone to xruns and generally
works well but I've still got a couple of niggles/questions.

1) How do the -n/-p parameters relate to their counterparts in jack? Should
   I be specifying exactly the same -n/-p pair for the closest sync?

2) When I capture a mix of jack driven and zita-a2j driven inputs, the
   alighment is out. I don't just mean audio latency, I mean that the
   captured regions have different start times. I'm guessing something is
   trying to be smart about re-aligning the two sources but it's not
   getting it right. In addition, by moving the region starts it seems
   to break the edit-group synching of region edits.
   
Note that I'm running these cards clock synched at the same sample rate so
that oughtn't be an issue.

bjb