Can you recommend a 12" portable trimmer? I currently have a fiskars 12" portable trimmer. I need to replace it. I have never liked it because the measurements are off -- when I try to cut a piece of paper in half, one is always larger than the other. also, a 4 1/4 inch cut is common for me and you kind of have to make a guess for that measurement. I am obsessive about making sure that my photo mats are cut perfectly. I often use the perfect layers system and an exacto knife, but it would save me time if I could find a cutter that I can work as consistlenty as perfect layers. Any suggestions?