SO, I managed to find some time today to get the z-axis mounted on the sled and it worked so well that I decided to go ahead and try my first cuts! I posted about that in Projects.
I am very pleased with the speed of the z-axis. I was counting to about 20 seconds for a 60 mm of movement, and during the actual cutting, the z-axis performed very well, and the tabs barely slowed down the cut. For the 1/8 inch distance that the axis had to move for them it was just a second or two.
The setup is the stock motor running to a 60 tooth belt gear to a 30 tooth gear on the lead screw. so i get a 2x speed bump there. The pitch on the screw is 2mm, with 4 starts, so that is another ~8x there. In testing it turned out that 15 mm pitch in the settings got me where I wanted to be with z-axis accuracy. It probably isn’t quite right, but I can work it out in more detail later
Here are some pics and video:
plan view of z-axis: https://goo.gl/9ZFv9e
angled view of z-axis: https://photos.app.goo.gl/c9D4RoszWBzJzvKG8
side view:
video of raising the axis 60 mm. It takes about 18 seconds to make the move, which comes out to a little over an 1/8" per second or 3.33 mm/second (this is with no changes to the defaults):
video of going over a tab (the small amount of time for the z-axis adjustment makes me smile 
)
Video of peck drilling a circular pocket (the CAM descends into the workpiece, then circles out the hole, then lifts to safe, at .25" over surface, and goes again, in .1" increments with the last being .05" for a total of .25". Not the best way to do it, but I didn’t feel like fighting with the CAM on it). The hole (pocket) is meant to be 0.17" diameter, drilled with a .125" endmill. The end result was closer to 0.21" diameter. Hopefully I’ll be able to fix this with calibration: