Digital BW, The Print

>[snip] My [Daniel Perez's] question is, can I print on 260gsm Museo with the
>+/0 switch set to 0?  Anyone tried this? [snip]

I have inadvertently tried it both on a 900 and on an 1160 with 
Crane's 300-gsm/110-lb, about 11-mil,  cover stock, without incident. 
But I don't do it deliberately for fear the print head might 
accumulate damage not immediately apparent.

Sam