Using speedbrakes with more than Flaps 5 (737)/Flap 1 (A320) is discouraged due to buffet and increased stall speed and never use speedbrakes below 1000' - completely agree.
I think the FCTM states not to use Speedbrake with flaps 15 or greater, so technically you can extend your speedbrake up to Flaps 10.
1000' AGL as the maximum height to use it (limitations section).
At least on the EFIS series, Denti can enlighten us with the NG's
Happy Landings!!!
