I feel your pain. Even with EmptyConfirm set and running everywhere I still lose characters to the input buffer. The most common situation for me seems to be with the combat shotgun. Everything will be going great, then I'll have to fire at the same spot in the dark a number of times. Move the cursor, reload, move the cursor, reload, move the cursor, oh crap that last reload didn't take because there was tobacco stuck under the 'R' key (it happens more then you think), now I'm walking instead, then I'm dead. Sure I could quit smoking, but that's never going to happen.
So yeah, I'd be happy to see this feature, not during speed runs, but definitely during YAAM U Ao100 runs (without master traits, yes I do this often).