Crooked cuts making it almost impossible to get decent double-mats was the main reason I swallowed hard and bought the "standard" basic model Speed-Mat 40x60 cutter. Almost everybody I know who does mats seriously on their own has this machine or the smaller 32x40 version. Bottom line is it allows you to cut PERFECT mats first time, every time -- single, double or even triple mats, 4-ply or 8-ply -- it chews though any of them effortlessly. It also has a built in trimmer for initial sizing. It aint cheap, but it's one of the few tools I own I feel has fully paid for itself, and that was after double-matting just 24 16x20's for a show... Details here: http://www.speed-mat.com/

Cheers,