I used to roll the toe, however, both farriers that I work with said no. If you get the break over on the front wall correct, you don't need to roll anything...Now the way both farriers taught me to take down the toe, was absolutely not to roll your nippers in any way, but keep them straight and take the toe down. Seems to work better than the way I was doing it. Thanks for the reply, appreciate it Loosie!
To be clear, you're doing a good job and this is getting into details where opinions differ.
I agree with keeping the nippers flat when taking the hoof wall down. Or you can use them differently if you have the same goal in mind, which is to not take the wall below the sole ridge in the toe. I personally don't want my sole to be the highest point in the toe, I want some hoof wall supporting. So keeping the nippers flat would be one way to ensure that didn't happen. I think it's important to understand not "what" to do, but "why," and then you can reach your goal any way you like. So if you tend to nip crooked and need to rasp wall down to get it level, you'll want to leave extra height so you don't have to rasp into your toe sole and thin it in that very important area under the coffin bone.
It is important is to realize that the hoof wall grows down and forward.
Why does the hoof grow down and forward toward the toe? I believe it is because of wear on hard surfaces when the hoof breaks over. If you look at very healthy hooves on hard ground, they wear the breakover back to the waterline of the toe. Since a lot of horses aren't getting constant wear like that, it can be very helpful to trim the toe wall back to the waterline to keep the breakover correct. Otherwise your breakover is going to be too long very soon after your trim.
Some do this with a roll, or you can put the nippers perpendicular if you prefer and just take that wall back that way, keeping the bottom flat. Either way, if you simply use the nippers completely flat and don't finish the edge with a rasp, the horse can cut himself on the inside of his legs.
Here's an example of a hoof where you want the breakover back, which you can't do just by trimming the hoof wall down flat in the toe. For this horse I would absolutely trim the wall back to the waterline to help it begin growing down at better angles and to relieve pressure on the stretched laminae. What in my opinion is flexible is how you do that...you can just chop it straight back, or roll it up from the waterline, or round it back from the top as long as you only address the lowest part of the hoof wall and don't rasp higher up.