The difference between Muff variations can be seen in the build document by comparing all versions especially studying only the components that will make a difference tonally. You will see that there is not a lot of difference between variations by component values that actually matter. You can also read up on the Kit Rae page which is also linked in our build document which already breaks every detail down about the variants to an exact science.
All of that said the difference between Muff variants is not very much. I agree that there is a small difference which is dictated by the values listed in the build document it should also tell you that it is not that big of a difference to warrant a massive change in the tone. Opamp version excluded.
My point is that there already is a lot of detailed information available. My thought is that there is not enough difference to warrant 8 versions. I agree with Wilkie in that you should “Socket” the board and test your own values and see what you like and do not be afraid to try other values not listed in the build document. Also obviously when using the Muff Tone control and where it is set will make more or less difference in the Roto-Tone settings. This is also highly subjective so we suggest “socket and see” approach.