The ball bearing flavor of the encoder looks like it has a really long life, depending on how tight the the drive belt is.
I was running a dos mode stepper driver setup until a few months ago when I changed to Mach3. I'm not going back to dos in this lifetime
And yes, there is a boatload of settings to play around with, most of which I have no idea what they do. It would be nice if Mach's default screens had a DRO and a zero button for the C axis, but I'm not up to messing around with trying to add one. I'm using the MDI, jog settings display and the voltmeter to set up the C axis anyway, so I can get by without a DRO for it.
I have a really hard time seeing the laser's focal point, even when it's not over the lasing threshold. I resorted to blowing some smoke into the beam when I was trying to find the focus distance. The beam's cone shape is pretty narrow with a focal distance of 4" or so, just a few degrees, so I'm guessing that a few thousandth's in movement up or down won't make much of a difference. I'm using a stepover of .010", and looking really closely at the picture, I can see the individual raster lines. From a couple of feet away, they're not visible.