The one that avoids all that is the Gerrard...
Yes, the Giraud provides a consistent trim length based on the shoulder position. So, if your resizing process is consistent, case length will also be consistent.
Something to note, however, is that if
there is some variation in "shoulder bump", the Giraud will only trim based on the shoulder, so variation in case length will be evident after trimming.
It really is two separate things to chase -
Control resizing so "cartridge headspace" (head to shoulder) is consistent.
Control trimming so shoulder to mouth is within safe limits.