Digital BW, The Print

I've got two large prints I need to have made for a client.  I have 
an Epson 2200, and love the output (using ImagePrint for B&W), but 
the prints (16x20 and 20x30) are too big for me to do myself.  I will 
likely have them do the color print on the Epson 9600.  The B&W is 
20x30 and I'm not sure whether to have them do it on the Piezo 
printer or the Epson 9600.  My primary concerns are price (the Piezo 
print costs about 2 1/2 times as much, meaning I have to charge my 
client a comparable amount) and possible metamerism if I have it done 
on the 9600.

So I guess the question is, does anyone know whether West Coast uses 
an RIP like ImagePrint to reduce metamerism or whether they're using 
the regular Epson driver, or does anyone have any personal experience 
w. B&W output from West Coast?

Thanks!