The DS-500 is probably the brightest taillight money could buy, if you could still buy it. It's literally just their headlight with red LED elements in it-- and CREE XM-L no less. It's utterly unusable at night, but puts out the light it claims-- which is why it needs a massive 7.4V R/C-car-size lithium battery to power it. The Niteflux is claiming the same lumens for a light with a built-in 800mah battery.

It's all moot anyway. The OP is most likely trolling us all, and I'm certainly not going to ditch 150lm for $25 in favor of +200lm for $200+.