Time for me to chime in.
I work with the Museum of Neon Art (MONA) MONA / The Museum of Neon Art — perhaps the most pro-neon entity in the West. For years, the museum has been watching the progress of LED signs as a cheaper alternative to the art and craft of bending glass tubes filled with noble gases and phosphors. The technology for such LED signs hasn't yet caught up with its promises.
The lifespan of an LED sign can be measured in hours while a neon tube can burn for generations. Recently, a pair of neon tubes were discovered behind a wall in downtown LA. They were bent in the late 1930s, sealed up behind a wall in 1946 and have been burning brightly ever since. At this stage in the game, an modern LED sign cannot match the performance of a neon tube produced in the late 1930s (!).
Clifton Cafeteria: Neon light left on for 77 years discovered during Los Angeles restaurant renovation | Mail Online
LED colors fade with time and die completely in hot or cold weather. Examples keep popping up across the nation of LED signs that appear to save expenses initially, but then cost more in the long run with constant replacement as LEDs dim and die with the weather. Imagine leaving your iphone on a hot, tin roof for a year; it wouldn't work so well either. Neon, on the other hand, perseveres in hot and cold; it can even handle a freeze.
Also, the brightness of an LED sign is generally less than that of a neon sign, depending on the shade. Color options are also poor in comparison.
In terms of neon as an artform, it remains unmatched:
Museum of Neon Art, Michael Flechtner by jericl cat, on Flickr
Museum of Neon Art exhibit by jericl cat, on Flickr
MONA_Flechtner by jericl cat, on Flickr
Earl Carroll Theater, neon sculpture by jericl cat, on Flickr
Museum of Contemporary Art by jericl cat, on Flickr
It's A Gas exhibit by jericl cat, on Flickr