[...if you do a good clean job, and got most of the comb they'd probably make it with a little bit (or a lot) of feeding through the winter...]
I don't think you have done very many cutouts to understand the dynamics at play here. Doing a good clean job isn't always a matter of how good the beekeeper is, a lot depends on the location and contruction of where they are located. And you are making a broad and presumptious assertion that you can cut-out and rework combs into frames not only in a functional means but in a pattern that is ideal for the cluster size and brood pattern for the winter. Winter survival depends on a lot more than supportive feeding - if it were that simple a lot more of us would quadruple in size each year.
[I have quit doing cutouts for the year.]
As should I, but I guess I am pressing my luck on a few just to see what results I get trying to winter them as nucs instead of treating them as a full hive. I am feeling from previous experience that feeding too late is creating wetter stores that contributing to winter condensation. Dry feeding is a quick fix, but it fails if you don't have enough warm days to allow the cluster to break. Its considerate and not greedy that you aren't trying to hoard all the bees you can get - shows character.
-Jeff