have never used 50.2, but this things are common for any modern led.
pros:
big hotspot
no beam artefacts
low or no tint shift
cons:
small cd\lm in comparation with same size reflector - lower throw
80-85% efficiency, if you want 50W output be ready to melt your optics
I have used several different 30-35mm tirs, they work with cree leds very well, usually if you was annoyed by greenish tint of corona with reflector you will forget about this and wonder how pretty tint is.
I would also say that if you have experience with 20/24mm triple/quad tirs, please dont make conclusions about all TIR lenses. 3-4sq.mm die just cant be focused by 10mm lens. 30-50mm TIR work completely different.