I actually prefer to 'tear' (gently, not a ferocious 'rip') for long pieces - a press and, rarely a trim, and I'm good to go. I like border prints, and this is the best way I've found to get them as accurate as possible. I only tear lengthwise grain, tho - I think it could possibly stretch the crosswise grain.
Eddie, here is a site that talks about fabric grains:
http://www.sewaquilt.com/fabric-grain.html It might help to understand, at least :D