"For one, it's been compared to GORO. Perhaps there could be some similarities, but MXSG has no proven reserves, and has done little to prove what is possible, at least compared to what GORO had done long ago."
You are wrong on this. GORO went into production with no proven & probable reserves. Like MXSG they knew they had an economically viable business plan and chose to skip that whole process of proving up reserves. It worked out very well for them.
"MSXG, lacking funding or enough competent mining people, is stuck with needing a JV partner,"
The mining industry is filled with all varieties of JV partnerships which turned out very well in the end.
"Any lode mining, however, would definitely need to have much higher grades, as costs aren't what they were in bygone days."
The CEO has stated they expect a $400 cost of production.
"Further, if they do actually start producing, I believe the terms call for MarMar to receive all the revenues until their expenses are met,"
Not a big deal. MarMar's expenses will likely be paid in full with the first pour and then all revenue from there on out is split 50/50.