I wanted the red and green inks too. Do not worry about it. Heck my 6ink epson r280 consumer printer had the same gamut of the pro100 which is very similar to your pro1. So no, red doesnt matter for color gamut. Maybe it might be a slight more pleasing, but its not that much worse.
Is it darker yes, but I guess that just adds to the B/w capabilities. Its not darkroom B/w, but pretty darn good for digital. There is not grain, but i think you can by specialty baryta paper from manufactures.
Again for red, its great and saturated when I produced a pure red print.
Another reason to switch is longevity of the inks. Not sure about your printer but is it a chromalife100? cause now there's the chromalife 100+ which is about 5times more resistant to fading. I heard terrible thing about the early inks that are dye based. But this only matters if you have your windows open to sunlight.
And if you have the MK1 of the 9000 the pro100 is going to be much much faster like your pro1.
And ink consumption is down as well. Barely eats any ink during cleanings. And is sooo quiet.
A good printer overall.