I've tested this to extremes 'cause I really am that dull. The same 300mm x 300mm print. Two versions of the file a 300ppi tif and a 200ppi tif (down sampled from the 300ppi) great quality start file. (Note: the res is at final output size.) Printed side by side on the same machine (HP5500) at the same time (so same in all respects other than ppi of original file.) I couldn't see a difference. Under a lens I still couldn't see a difference. Over a month of asking people which they thought was which I got close enough to a 50/50 response that it was clear that no one could see a difference!
Far from looking crap at 200ppi. With wide format digital print you never need to go above 200ppi at final output size.
As a quick tangent.... Folk often say dpi when they mean ppi. Worth a thought because they don't mean the same thing and they're not interchangeable. Files contain pixels, thought of as square, each of which is normally one of 16.7million colours. Printers fire dots, which are thought of as round, and tend to be one of four colours. They are nothing to do with each other, and don't relate to each other in any way at all.