I used a Dexter as a student years ago, and it doesn't compare to the Logan cutters. For one thing the Dexter blade is thicker, so the over cuts are much more obvious.
You might consider the Logan 301 - I believe it is the same as the 350, without the measuring rule and the square arm, and is less than $100 USD. I would never trust either one, especially the squaring arm.
I measure a rectangle and mark it on the back side of the matte (with either Logan, you mark the back, not the front side, like the Dexter, IIRC), then cut using the rail guide, which, on mine, is reliable and stays parallel when adjusted for width. Also, for long cuts, if you keep the cutting tool in place, you can slide the whole matte board and continue cutting without a hitch in the edge.
It also comes with two cutting tools, one for bevels, one that cuts straight down, nice for cutting the outside, and for cutting foam core.
But the big reason for going with the cheaper model - you can wrangle another present from him with what's left over - like blades - or matte board - or dinner. . .