For those of us running Aux Fed subs, it would be great to have a finer level of control over the cross over region. On the Ui-24 for instance, you can select 12, 24 or 36 db/octave slopes for the hpf/lpf. This would be a huge help for Aux Fed subs.
Note that I am breaking my previous suggestion into 2 separate topocs as suggested in that thread.