I can only speak for those of us who still drive the original -200:
Boeing 732 Operations Manual Vol 1 limitations ( L.10.10 ) states: "Do not deploy the speedbrakes in flight at radio altitudes less than 1000 feet."
As for the speed limitation, there's non, except do not deploy past the inflight detent in flight.
Lastly, I've found the speedbrakes to be very effective in slowing down this bird when the need arises.
It's all about airspeed....