To be honest I think people in general underestimate small "secondary" adjustments like this, which I personally prefer over directly gutting a unit's performance. Units like Assault Engineers, Pathfinders and Assault Grenadiers, Valentine (and Jaeger Light Infantry) have all been (imo) balanced simply by changing their call-in conditions in order to regulate their availability, while leaving the per-unit performance of these units largely intact so that they can remain strong to serve their purpose.
I would much rather try creative secondary solutions and see if they work in the long run, and make further (performance related) adjustments later in case they ultimately do not (fully) work, than straight up going after performance and risking a unit to go from overpowered to underpowered (which has happened a lot in the past).
6-9 extra popcap over 2-3 Churchills is a pretty big deal, as that's going to be 1-2 fewer Royal Engineers to repair or 1-2 fewer other units to support them otherwise, which should make pure Churchill spam less attractive.
Great post,+1