We have a similar system our aeroplane and while it does a good job at maintaining 3°, if it is "bumped off" the nominal 3° path by whatever, it stays "bumped off". You have to put it back on the charted slope. If you don't, you'll end up going in short or long. You must closely monitor the profile and intervene with FPA adjustments to maintaining the charted slope, especially when limiting steps are involved.
My impression is that too many think that these "wonderful" CDFAs are simply "point 3° from the FAF and all will be OK". Not so.