For our core rule-book, we were looking at initially detailing the Red Martians as the PC race, and keeping Green Martians, Earthlings, etc, for soon-to-be-released supplements. The idea is to keep the core rule-book focussed; to get it out soon; and to give players an opportunity to explore Barsoom as a 'native' first before tackling it as an outsider.
It sounds like Baron Greystone would prefer an approach of having more races, albeit less detailed, in the core rule-book. Is that accurate?
I don't know that keeping the core book 'focused' in the way you describe is a goal I'd agree with, per se. I think the core book should be a one-volume, stand-alone game. Supplements should be just that, supplemental. If your concept of the game is that the majority of pc's are Red Martians, that's fine. Just like D&D expects humans to be the majority of pc's. But the core book should also allow for simple versions of Green Martians and Jasoomians, because their presence is core to the novels you're trying to recreate, and some players will want to try them right from the beginning. For instance, the Chaosium Runequest 2nd edition book (old-schooler, remember) is focused on playing humans. But there is enough information on dwarves so that you can create a PC dwarf. He may not be all that different from a human PC mechanically, but there is a nod to creating something a little different. Or think of it as the difference between creating a character using the original Little Black Books of Classic Traveller, versus a detailed character using the supplements Mercenary, High Guard and Scouts.
Your two other priorities, 'get the book out soon,' and 'allow the players to explore Barsoom as natives,' are not things I could agree with at all. Why does the book need to get out in, say, three months instead of a year? The movie is already old news. And if I want to explore a land and its culture, I don't want to read up on it all and create a native -- he already knows everything, he's a native. I'd rather play, a la Empire of the Petal Throne, a newcomer just off the boat. That way the players can explore a world that is completely new to both them and their characters. Both they and their characters gradually build up a store of knowledge through actual exploration. "What's that purple plant?" A native knows it is carnivorous or hallucinogenic, and immediately responds, "Oh, I get my whatsis and that's no longer a problem." A newcomer asks, "Describe it in more detail. I observe, does it move? Look for clues in the immediate vicinity, any signs of prior creatures meeting a terrible fate? How does my little animal friend, a native to this land, react to the purple plant? Does it ignore it, does it hesitate to move forward, does it growl? Maybe it's a source of water, does it appear to be a succulent plant?" After our new players and their non-native pc's have accumulated plenty of information and explored, it's time to allow for native pc's, and the game's focus changes. See what I mean?
Hey, I wish you good luck and am interested in what you produce; just taking the time to give you some feedback from one potential customer, take it or leave it and no hard feelings either way.