Reciprocating Laser Cutter - real world feedback anyone?

[ElectroNick]

In the process of considering various DIY laser cutter designs, I'm curious if someone had built and gained some experience in running a laser cutter which moves its laser diode up and down (to increase cutting depth, for example). Something similar to the one described at Thingiverse: http://www.thingiverse.com/thing:3902

How does the cut look like and how do you guys sync the reciprocating motion to the horizontal one?

Thanks for your input!