Your original question(s) cover a lot of ground. I want to address your question regarding Richardson and follow up with the kinds of sources that are acceptable to the Magna Carta Project I will give an answer in keeping with my understanding of current Magna Carta Project policy and practice. My current affiliation with the project is that of co-Leader.
You asked: ''I am not wishing to cause controversy, but it seems to me that some folk consider Richardson to be the sole source of information worth considering''.
The Magna Carta Project was founded to document, explore and improve the bios and lineages of the 17 Magna Carta surety barons known to have descendants living as late as the 17th century and whose descendants immigrated to the American colonies. These early colonial immigrants are known as "Gateway Ancestors". To assist in this task the works of Douglas Richardson , in particular, "Magna Carta Ancestry" was chosen by the Project as the foundational source that the project's work would be based upon. The reason for this is that Richardson's compilations are considered to be generally very reliable, are supported by primary sources in most cases and they provide a ready "at hand "source reference to assist in the documentation of project approved Magna Carta lineages. However, Richardson is not considered by the project or it's membership as the only acceptable source and Richardson's works are not considered by the project as being infallible. Alternate, high quality sources are also allowed as long as the validity of these sources can be ascertained and firmly established. Here is the Magna Carta Project written policy in regards to Richardson and other acceptable sources: "Magna Carta Ancestry and Royal Ancestry by Douglas Richardson are the foundational sources for the Magna Carta Project. Where there is a conflict regarding the facts on a profile, we follow Richardson, unless there is more recent published research that adds to or corrects his work. For details on implementing this policy, please see Magna Carta Project Policy and Procedures" I would also add that primary sources are always acceptable, if these sources (usually consisting of transcriptions) can be validated and are properly cited.
To answer your 2nd question regarding the value of research I would say that any effort that adds to our knowledge or that uncovers and corrects existing errors in the current biographies is important. To this end, with the ultimate goal being increased accuracy and knowledge in the subject, serious research supported by reliable sources is encouraged and welcomed by the project.
Thanks for your question !