There are numerous changes that occur to brass when fired. The application of instant heat and pressure that creates near instant expansion in the chamber, and then a quick reduction that results in the brass contracting. Taking into account microscopic variances and inconsistencies in the chamber, powder burn rate including air spaces in the powder, and the shape of the powder in the casing, (on the bottom portion of the case when inserted in the chamber), bullet seating, etc., the brass changes each and every time it is fired. This weakens the brass, and as you note contributes to what you describe as "developing a skinny waist", and eventually cracking and deformity that renders it no longer useful.
Nothing, including roll sizing will make multiple fired brass equal to that of once fired. It should however provide a little better level of uniformity and consistency between each piece of brass and thus load to load.
If you do go that direction, in addition to paying attention to separating by head-stamp, I would record number of times fired, etc. and see how it compares to actually firing once fired.
