I haven't really gone to the dark side yet, and still prefer the look of the old incandescent. I did try them a while back, but was not convinced. I have a few games that I received with LEDs fitted (MM, Elvis, MB and SM) and they look OK on SM, MB & Elvis, but no so on MM to me. As I have a lot of Capcom games and they don't like LEDs, those haven't been tried.
All that said, I suspect the quality has improved a lot and I might have a fool around wit them again one day.
MM looks good with led in the inserts and incandescent GI.
Yes, that might improve it...Maybe one day when I need to do a deep clean, I'll swap them out.