i've been thinking. the ram cart(all models) is not actually a game, because there is no pullup voltage on the cartridge pin(forget which), this is why the sega cd can load while the cart is plugged in. that being said, it is still a mystery if they bothered to region lock a bunch of sram chips.
I own a model 1 us ntsc genesis, and a model 1 us ntsc sega cd unit, and I wanted to purchase an ntsc japanese mega cd backup ram cart. will there be any region problems preventing the save system from working with cd games? (I am aware the cartridge may not fit in the us slot, that is not a problem.)