Yes, I know. But, this is the D20 forum so I don't really take it into consideration when talking about rules for the setting...
My opinion differs. Rules are reflections of the setting. They simplify something that is, conceptually, every bit as complicated as the real universe in order to make it playable. Different rules sets do this in different ways, depending on what aspects of that very complicated "reality" their authors felt like highlighting. People of the OTU don't really operate in character classes, you know. That's only a game artifact of T20. Just look at some different RPG rules based on the very same historical setting, and you'll find that they can, seemingly, feature some very different places where only the names are the same. T20 supposedly describes the very same universe that, 125 years later, were described by the MT material. Inevitably there are some discrepancies that can't be explained by changes in practice over 125 years and must be reconciled by deciding that one or the other (or in rare cases both) are wrong, wrong, wrong[*]. But with that
caveat, evidence for how the OTU works is evidence for how the OTU works, regardless of where it comes from.
[*] There is admittedly an added complication when it comes to a fictive universe like the OTU. If one historical RPG claims that the King's Musketeers of 1625 France had 120 men, all noblemen, and another claims that it was 600 men, officered by noblemen but manned by commoners, then (at least) one of them is flat out wrong, and if you can dig out the proper historical documentation, you may even be able to prove which one it is. For a similar discrepancy in the OTU, there's always the chance that it's a genuine retcon.
Hans