Hate to reply to my own post but adding intrigue... found some relevant info over on the sparkfun forums... seems others have had problems interfacing SCP1000 with other slaves on an SPI bus.
http://forum.sparkfun.com/viewtopic.php?f=14&t=19485&start=0
Can anyone suggest any mitigation strategies that don't involved software SPI? I'm going to comb through the SD library and look for dummy reads/writes and try changing their values - I know there is one in SDCard:Init... any other suggestions? Thanks in advance!