Funny enough I do have an ammeter hooked up, but after rebuilding my entire machine I re-wired it backwards so as of right now it’s not usable. Before I was using it just fine, and all I have to do is swap the leads. It’ll take me 3 minutes to fix.
I manually set the maximum X speed to 300mm/s (18000mm / m), so far everything is going OK. I had to up the stepper current a little bit though, after the motors could barely move at 100mm/s
My bad, I mis-spoke. I have the K40 with the digital display on top, which was simply a PWM controller where you could set the percent via the up and down buttons. After testing the PWM values from LightBurn, I found that the tube power output with the MiniGerbil and the original PWM controller from the K40 are the same with the same percentage (most likely same duty cycle).
UPDATE: I was taking a look at some of my engravings, and noticed towards every edge the depth of the engraving looked like the following:
**Looking at the material from the side
What I came to realize is I had set the X and Y acceleration with relatively low values, I believe around 500-600 (I forget the units, likely mm/s^2 or less-likely mm/m^2). The simple dip towards the edges would only make sense to be directly caused by the acceleration. And, LightBurn has of course thought of this, and created overscanning to allow the head to drift past the end of the part to avoid artifacts like this caused by deceleration. In fact, here’s a post on it:
Low and behold, my over scanning was disabled 
I will test this tomorrow as it’s late for me now, but I’m 99.95% sure this is the solution to the problem.