Regarding analog input, I think the more expensive control is worth the increased cost. In the final machine modification total cost, the analog I/O controller is relatively small.
All commercial machines use knobs for spindle speed, feedrate modification, and analog motor load meters etc.
I have two commercially built CNC mills. When running a new program, you are always watching the cutting tool, with one hand on the feedrate knob, in case the cutter feed, or spindle speed is too high. You can tell a lot just watching and listening. A tool can break in an instant, if a particular spot loads up the tool. It is easy to just crank down the feedrate, and edit the program later. Much less effort, than installing a new cutter, cleaning out the broken tool bits, resetting the tool offsets, and going back to the beginning, and possibly having to reset the machine home position. All this if you did not scrap the part!!
Looking up at the screen, and using the feedrate jogs is way too cumbersom, and takes longer. Look at all the posts asking how to add a spindle speed, or feedrate and what hardware to use.
I own a dspmc controller without analog, and wish I had opted for it. The controller is absolutely amazing. Plus, it is a great company always working to improve the firmware, willing to answer any question you may have.
Regards,
John