I just tried flashing for the first time last weekend. I used the RH Designs flasher mounted next to my enlarging lens. It has a nice test strip feature and digital timer. I pre-flashed the top half of the 16 x 20 paper for 32 seconds and dodged the rest while split printing thenegative. Made a big difference in the highlights.
However, post flashing would make it easier to gauge the desired effect so I will likely do that next time. The flashing device works very well.