Okay I realized today I am a revision behind with FluidNC.
I am in the phase everything works then i screw up. Most common forgetting to take the Z axis printed support blocks out.
How important is this update?
At this point feeling a little overwhelmed. 
Thanks
-Craig
If 3.9.5 is running good for you then I would just stay on that one. I don’t think there were any significant changes from there to 3.9.9
If it ain’t broke don’t fix it.
To get technical it is here, Releases · bdring/FluidNC · GitHub
For us the important ones are fix the probe to always work, previously it would just not trigger sometimes. And the thing with arcs messing up softlimits for those that run them.
We also moved from UIv2 to UIv3, but we are probably about to change to Mikes fresh build pretty soon on that one.
If you are comfortable and have not experienced the probe issue, don’t worry about it.
Thanks I agree.
I tend to worry about trivial details. I still have your 24v fan (well actually mine now 
) and want to install. I have everything but just not up to taking controller apart as I just did to do the LED light strip mod.
Then I saw this morning @jeyeager post about cold workshop and realized my basement is about 62º! So maybe the fan can wait!