it's the irreversible nature of flap extension that puts it to the bottom of the toolbox for me.
Why would flap deployment be irreversible? Sure, you've got to adjust pitch if you remove flaps, opposite from the pitch you need to apply when deploying flaps, but other than that flaps are just a flight control. To be used, or not, as and when required.
If you deploy flaps thinking you're too high and need more drag, and then subsequently find yourself too low, why not simply remove flaps, partially or fully?
I'm also a glider pilot so quite used to the use of air brakes. In a glide approach, I tend to use flaps the same way. The only complication compared to gliders is that the pitch required to compensate for flap deployment is more, compared to airbrake deployment.
The only way you'd end up in trouble when you remove flaps, is if your actual glide speed is below the green arc. But as Vbg is normally very close to Vy, you should be well into the green arc in this situation.