I don't know if there is a valid comparison to be made between the
relative effectiveness of the lower filter numbers compared to the
higher numbers ie that soft negatives are more responsive to higher
grades than high contrast negs are to soft grades.

Its a matter of perspective.

Once you think about the process it becomes apparent what is going on.
When developing essentially what is going is a cramming effect, a
cramming of a high brightness range into a small brightness range. This
is because paper inherently has a small brightness range. Negatives have
a higher range than paper and real life (ie sunny days) has the greatest
range of all (obvious when you think about it). So developing negs is
essentially a balancing act (expose for the shadows and develop for the
highlights) of putting enough range into your negs without overpowering
them.

Well, it is easy to do - overdevelop. Once this is done it is almost
impossible to rescue. Cram a huge brightness range (negs) into an
inherently more limited medium (paper).

Hence the higher grades are (usually) more responsive than the lower
grades...

Many high contrast negatives can indeed be tamed by using a lower contrast
filter with VC paper. You should try it and see for yourself. If you are
technically inclined, Phil Davis's book explains the concept thoroughly.
It's a matter of matching the density range of the subject in the negative
to the sensitivity range of the paper with a particular filter.

Whether high number filters affects the contrast more or less than low
number filters seems to depend on where you start from. Certainly, high
contrast printing has much more sensitivity to exposure that low contrast
printing. Perhaps that creates the illusion of a more potent effect.

Lowering the contrast will work only if your shadows (especially when they are prominate)
are adequately exposed.

Realistically the mid tones and shadows will need to have enough detail, I have seen
negatives that lacked shadow detail and midtone detail, and I have seen negatives that just
lacked shadow detail. If its only an issue of the highlights being a little over cooked
you can probably adjust  them down with printing filter control and additional burning in.

The only dumb question is the one left unasked.

I don't think so. Here's a way to compare them:
http://home.earthlink.net/~belinkoff/darkroom/calibrate-dichroic-head.pdf

If you look at figure 2, you can see exactly what the grade pspacings
are for various variable contrast papers.

Do you have a negative that requires a low contrast filter? If so,
your developing is probably too long.

Different brands of variable contrast papers respond differently to the
filters.  The low numbered filters will lower the contrast, sometimes a
lot, and they may work well for your negatives and paper.  If not, you can
try other papers.  Kodak Polymax is especially designed to have a very wide
contrast range.  Others may be as good.  As a last resort, you could try
prefogging to reduce contrast (see Ctein, "Post Exposure.")