I asked Simon and he says “the LED is out of stock currently.” If you/anyone is interested in 519a and don’t want to wait it would seem Banggood is the way to go while they still have them in stock.
I highly recommend the 519a also. Whereas 219b has that famous rosy/magenta tint (a result of a negative, below BBL Duv) that every hobbyist loves, 519a has a warmer, more yellowish/golden tone (a result of a positive, above BBL Duv). During comparison, I actually was struck at how different 519a is from 219b. See the hat crops from beam shots of my living room below (thanks Jon) - besides the red hat, notice the background. The window blinds are very slightly off white in real life.
I like the 519a because of how different its beam color is from 219b, and yet it still has spectacular CRI specs ( Ra 93.6, R9 82, R12 80, Duv 0.00091). While 219b has better R9 (reproduction of red), sometimes the magenta tint of 219b might be too much , and 519a’s golden tint provides a relief. In other words, like having different wines or food from different restaurants, all good yet different. I guess it’s called having fun with a hobby. At any rate the pair would make a great great back bone to any collection where CR and /beam color & quality is of prime importance