Why do you think blue worms (tropical worms seldom sold in the US) will do a better job than red wrigglers (adapted to our climate & widely available here)?

I've seen blue worms sold in combination with red wigglers in the South, including Georgia and Alabama. There was a demonstration garden in Huntsville I visited which had a large compost pile utilizing red wigglers and blue worms. The blue worms were amazingly active, even compared to the wigglers. As I recall, the blues were an accidental addition to the pile, but did thrive there. I believe the lady I talked to about the system also said that it would be hard to get a culture of just blues separated out, but that the combination was a good Southern idea because the blues migrated well into new areas (this pile was in the middle of a large yard work area, with other piles near by), and they could tolerate the heat and humidity of the summer well in the upper portions of the piles, while the reds would move down some in the summer to escape some of the heat.
Renais