Please don't take this is in a bad way but this says to me that you might not quite understand the interplay among the three base values—inlay-material, air-gap, and glue-gap (A, B, and C in my post above). The B and C values in a way don't really matter at all. They could both be zero* and I could get an inlay to work properly no matter what angle v-bit I was using.
When glued together the plug and base will touch on all flat faces (at the surface and in the pocket),
* technically the "V-Carve / Engraving Toolpath" requires that the B value to be non-zero (e.g. 1/1000 of an inch).
Perhaps. It really depends on the design you are trying to do. For example if I were doing the following simple star using a 30 degree v-bit I'd get this result:
But if I were using a 90 degree v-bit I'd get the following result:
Both are using the same A, B, and C values. It may not look like it in the images but the flat depth of the star in the base and the flat area depth around the star for the inlay plug are both the same with both 30 and 90 degree v-bits.
Is one better than the other? Not really. But, I'm more likely to have a 90 degree v-bit. And the slope for the 90 degree v-bit provides a larger glue area which might prove usefull.
It depends. For the star above not much. For a design that has fine features the steeper the bit (smaller included angle) the more potential for material to fit into the base and the less potential for chipping of delicate material.
So it's better to say the the design might dictate the choice of the v-bit. Some of those cutting boards created by Stephan Forseilles need a seriously steep v-bit (small angle) for the tiny lettering and thin lines to have a reasonable amount of material inlaid into them.
The following design uses the same values for A, B, and C.
This one cut with a 90 degree v-bit has many areas on the plug (and in the base) where is details come to a sharp peak. If this was delicate material there could be much chipping. Also, some of those peaks might have less material than I want to inlay into the base.
This one cut with a 30 degree v-bit has far more flat areas on the plug allowing less chance of chipping and a better chance that the the full depth of material will inlay into the base.