The MSX2+ wasn't sold in America either - I think that also was Japanese exclusive; even if it wasn't who wants to import a 220V machine? As I've said before - I really should test this out in BlueMSX - if the Turbo R runs Undead Line, that'd be a real pro for the system. I've no clue though since it either emulates the VDP of the MSX2+ or includes one; neither seems likely to offer different performance. I believe I've seen a list of the Turbo R exclusive games, don't recall anything that stands out.
The only thing I'll say is that any Turbo R exclusive I'd want to play (Illusion City?) I'll emulate.