.....ahhh my favorite tin snips. I have all three - straight, left and right. Had 'em for probably well over 20 years. The straight ones are dull, so I do need to cough up some bucks for some new ones.
I also have these and they do an even better job of cutting a straight line without distortion, but do leave a 1/16" curly cue.
http://www.jilson.com/shears.htm
Dave W