You won't weaken the reed if you don't gash it. Recently I took a pair of MS reedplates in low D and throroughly reworked them - embossing, re-setting gaps, tuning to just. Near the end of the process the Draw 6 reed fatigued and broke. It snapped off along the line of a tuning gash near the root of the reed. I had not altered the pitch of this reed by more than a few cents and it had seen very little playing time. Rather than replace the reed, I decided to just rework another reedplate. But the Draw 6 reed on that plate had a nearly identical tuning gash, and with far less work on it, that Draw 6 snapped off along the same gash line.