I have one that I use when printing RA-4. I have a roller processor, and find loading exposed prints in in the dark is fine, but sometimes things have been set down on the lid, and they go flying when I open the lid in the dark.

Mostly it helps figuring out where you are turned in the room. It was more useful before I had fitted the Omega D5 in as my primary enlarger. It has illuminated dials for flitration that help me not bash my head against the enlarger head, as I was wont to do with the prior enlarger without use of the #13 safelight.

Mine is an indirectly aimed little safelight - glass of the size of the Kodak duplex safelght. 7.5W bulb.

You need to be in the dark for quite a while before your eyes begin to sense that this thing is even spilling any illumination out at all unless you are looking directly at it.