I have seen people cut a packaging foam piece the size of one of the dose sections and it sweeps everything out without using a brush it works great and doesn't fall out.
Our NS MCF doser leaves hardly a trace behind, assuming you work it through the whole dose cycle. I wonder if there's an adjustment issue, and the partitions on some of these dosers aren't flush with the bottom?
I thought at first you all must be talking about the throat, between the burrs and the doser, where we do get a teaspoon or so of grounds, as I guess may happen with any grinder. Doser or not, I'd want easy access to the throat to get that stuff out - sometimes it's decaf.
We pour a single dose in the hopper. We can estimate that as well or better than a untamped mound in the portafilter, and that's how it's going to be anyway if the next dose will be a different coffee. I've used a doser-less Solis, didn't like that.