Digital BW, The Print

I recently set up a 1280 with a CIS/Piezo system.

While it prints  well, it is much slower than my 1160.

Am I correct in deducing that the "Best Quality" Piezo setting makes 
the 1280 print at 2880 dpi regardless of the Epson dialog settings? 
Or is this just a 6 ink vs. 4 ink thing?
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