If you are cutting dados in a single pass, it really does not matter IME.....I like to pull the router to me when I'm cutting dados on the rail because it is easier (with the 1400). That said, if you are doing multiple passes to make a dado wider than the diameter of the cutter you have to pay attention on the second pass so that you avoid a climb cut. There are circumstances where a climb cut is appropriate for cleanup but my explanation for people is to compare a climb cut on a router to feeding a board through a tablesaw from back to front. One other tip for routing dados on the MFT, IMO is to start the plunge about 1/4" from the back edge of the work which creates a chip dam for dust extraction, pull the router towards you and then take out the dust dam last.....routers are messy enough....oh, and using some sort of cyclone will save you lots of CT bags. One other little tip is that if you are making dados for something like a bookshelf, you can do all the dados before you cut the sides apart and everything lines up automagically....
