This is excellent news.
With the new additions, I may just keep and use this card instead of the CSP, since I've got Chase Ink cards. The 2X dining and travel on the Ritz may be more valuable, now that I can redeem and use it at all Mariotts.
Are Ritz Carlton reward points and Marriot points transferrable between the programs? I've thought about getting the Ritz card at some point but only if I can transfer the points to the Marriot program if needed.
They're essentially the same, in that Ritz Carlton points can be used to book Marriott rooms and Marriott points can be used to book Ritz Carlton rooms. You can only be in one program at a time, but you can change programs just by contacting them and asking to swap.
The only real difference between being a MR and RCR member is what promotions you get. MR members will usually see Megabonuses, while RCR will get promos like stay 4 nights at a RC and earn an extra 30k points. RCR runs that promo once per year it seems, usually around summer.