The intensity slider should go up plenty high enough - if we are using real life examples , then 300cdm2 is about as bright as a computer screen 10,000cdm2 is about as bright as a fluorescent bulb.
If it is looking too dim it could suggest that either the rest of the lighting in the scene to bright relative to that or perhaps the glass of the geometry is interfering with how it looks?
The luminance of the 'self-illuminated' material is at it max (100,000 cd/m2
Camera exposure 34%
Sun brightness 0%
Night sky brightness 13%
Artificial light brightness 180%
Ambient brightness 100%
I'm using a sky-box of a brightness of 6,105.03 lux
For the time being it looks good for our office standard. I will take another look into it sometime later.