Non-headlight LED conversion has the potential benefit of better visibility during the day. I did the conversion on my XKE because the lights are small and low. The LEDs made a big difference in their visibility in bright sun, especially the front ones which now flash amber rather than white. Good when drivers can see you braking and/or making a turn. I am doing the same now on my Porsche 356 (next to the Jag in the pic), for the same reason and now that good LEDs in 6V are available.
All of that said, I have NOT done the conversion in the 250 as MB has generous sized tail and front lights which are quite visible with incandescent bulbs.
Today, compared to not that long ago, the conversion is a simple bulb replacement and an electronic flasher. And, cheaper too.