This is not a tool that I use all the time, as finding the just the right amount of reed to cut off - and even knowing when you have made the correct adjustment of the reed - can be tricky.
I have ruined at least 5 reeds, that may have been playable from rubbing on a re-surfacer by chopping off too much from the tip.
Some markings on the tool, indicating the starting position for the reed, could be useful in order to offer some (literal) guidelines to position the reed before trimming.
The other issue I found with this particular model is that it's not very sharp. Some reeds trim unevenly, and there are often bits of cut reed left between the end of the trimming tool and the the top area of the trimmer itself.
A few more improvements to the tool could make it more useful. For now, it remains nothing more than an interesting desk decoration in my studio.