In an operator’s modal keymap it’s perfectly fine to have undo/redo as ctrl-z/ctrl-shift-z which is friendly to use when your right hand is on the mouse and your left is controlling the keyboard.
Fishing for the backspace key with your left hand is weird isn’t it?
I’d be happy to have any keys doing one operation undo.
I just happen to have a strong muscle memory for the Backspace thing and I’ve seen it implemented in a wide variety of similar use cases.
Against the Ctrl+Z I can only say that it feels a bit strange for me to hit a two button shortcut while in an operator.
I dont really know if someone ask you but is is hard to make possible cut through multiple object editing?
Yeah, I thought that too after my original reply. Being modal it would be more convenient to use ctrl-z. Although I’m not sure if the global undo would make it weird to use?
@koloved , got same suggestion above. Task for multi-object editing was created long ago but not landed yet ( T56948 )
+1, for undo/redo, better to be consistent and use ctrl+z/ctrl+shift+z. Use of backspace key is not a bad idea.
Thank you 
This is great! I can agree to what was in the original post / other posts.
The angle snap and how limiting that is, is definitely annoying or breaks down my speed / creativity I feel, so I’m glad to see comments/thoughts on the angle snap/snapping in general.
Slicing via Global or Local XYZ would be awesome, and at 5 deg increments, or user specified/customizable increments would be great :).
Also as someone said, maybe hitting backspace to delete the last cut/vert may work well, or something along those lines, while the tool is active.
Also, generally cancelling is done via RMB, which I think may be ok… Although Extrude, I think it was, if you “cancel”, you don’t actually cancel… it leaves overlapped geo, which is very bad. That needs to be fixed, but that’s another bug/topic. But we definitely want a true cancel operation in here still.
Thank you!
@mattli911 Hi, thanks for the feedback!
Yes, plan is to provide UI so that user can adjust the angle value (:
In our company we are using RMB as viewport pan, so it doesn’t interfere knife tool at all.
Not sure if it is a part of a knife tool, it sounds more like CAD precision tool, like Polycross.
I would like to also add, i use RMB to Viewport orbit 
This feature could be a separate tool. Nice idea though
I have a lot of nits to pick with the knife tool but the only one that routinely drives me crazy is when geometry just fails to slice because the raycast hit the wrong face/edge/whatever rather than taking a heuristic approach and understanding what my intent was.
here’s a scenario I run into a lot: I have a boundary that i’m trying to close, but the knife tool snaps to geometry that is on the other side of the boundary and fails. This drives me insane
I realize that this is a weird one to describe via text, so here it is in video form. Keep in mind also that my real world situations are much more complex than this- I realize that there are easier ways to fill a hole in a box… would that it were so simple. Anyway, hopefully this makes sense:
Hi @testure, this is more kind of bug, you can submit the bug report at https://developer.blender.org.
Suggestions are welcome here . If you have more ideas you can add them on Right Click Select
wait so do you want suggestions here or on RCS? 
Generally RCS is best place to suggest features and ideas but ideas will be unseen from other developers. Just saying because you’ve more ideas for knife tool and all would not be possible to be done during GSOC period. If you have one or two suggestions, fine to add here (:
Side note- having submitted things like this in the past, I would guess that a bug report with this issue would be closed as invalid. Typically behavior that was not accounted for in the design of the tool seems to be dismissed, and only reproducable ‘errors’ get any real traction.
in your case you need to hit “K (knife tool) - Z (activate cut through)” to cut not closed geometry you created in the video.
And yes, snap to the middle point for this kind of shape would be nice feature for Knife tool.
Actually no, that would slice all the way through the mesh including backfaces. What I need is the specific thing I described- a heuristic raycast that understands the intent behind the cut and doesn’t just blindly grab the first thing it sees. I appreciate the workaround, but I’ve been using blender for many years and I have workarounds coming out of my ears, that’s not why I posted.
This thread is about improvements that can be made for the tool during this GSoC, and if this particular improvement can’t (or won’t) be made there is little point in discussing it any further so we can move on from it.
I totally agree with you.
But it’s not a bug as suggested to bug report it.
It’s just tool limits that, I hope, will be improved during GSoC.
