So what's the verdict?

This light works on a straight LT500 electrical system?

No other BS than plug it/wire it in to the existing system and it works?

I assume there is no Hi/Lo just wore it straight in to the high lead wire?

Thanks

The LED won't dim just by supplying less electricity to it (the low beam had a bigger resistor for that purpose), because the driver is set at a certain output to power the LED's.
It'll take a large voltage input range and modify it so the LED always has the same power going to it.
If you give it half the power, it'll still put out the same amount of light, assuming it's not below operating threshold...if it gets past that point it just shuts itself off.
The only way you can dim an LED is by changing the settings on the driver, most flashlights have a multi-click function that changes the driver's output to dim the light.
I doubt these light bars have an adjustable driver, but if a guy with a little IC knowledge could probably figure out a way to splice in a potentiometer to the driver and give it a near infinite adjustability.
The pot could be mounted on the handlebars, on the light itself, or even on the plastics.

My suggestion is to mount a separate switch and bypass the high/low beam switch (the high beam actually has a small resistor inline, so you're losing a few watts there), or you can get rid of the resistors and wire it straight to the LED to keep the OEM switch installed.
Nothing else is needed for the light!