The JAA exam answer for the super stall question is "swept wings".
Handling the Big Jets say both swept and T tails are involved. Unfortunately, DP Davies didn't write the exam paper. (A bit difficult now)
Having flown both the T tails (Dash 8) and a swept wing (HS125) I know they are both susceptible to the deep stall phenonema. Hence both fitted with stick shakers and stick pushers.
A straight winged aircraft isn't susceptible to a deep stall unless it has a T tail. That is, it does behave in a normal way with the stall untill the disturbed air blankets the tail and thus renders it useless in recovery. The pusher prevents you from going that far.
A swept wing aircraft is susceptible to a deep stall. Tail position isn't as important.
There was a brilliant discussion about this a couple of years ago on this site (possibly this forum).
I'll let the more learned folks explain the guts of it.