Keep in mind that when changing Magenta filter you will be changing exposure.

30 magenta change + or - will equal 1 full stop change in density

15 magenta change + or _- will equal 1/2 stop change in density.
Yellow filter does not affect the density as dramatically as magenta in fact very little.

When using a dichroic enlarger, changing grades with yellow and magenta will require a understanding of this.
I think this is why a lot of people advocate the RHAnalyser in use with a dichroic enlarger head.

I use condensor heads with VCfilters and I really only notice a big density shift when going up to G 4.
For diffusion I have a Ilford Multigrade head which has a keypad for density and contrast control and is easy to use.