You can see the actual kernal speed in the diagnostics screen.
Mach3 demo is limited to 25k. You can set it higher and you get no warning that the demo has this disabled and the setting doesn't 'stick'.
There is a note buried in the documentation that says the dmeo won't go above 25k. I also learned here on the forum that threading and a couple of other things are also crippled, but not until after I wasted a lot of time and material trying to get it to work.
I suggested that it would be nice if there was a list of crippled features that would pop up when the demo starts so that people don't waste time trying to evaluate a crippled feature. No response from Artsoft on that thus far.