Demon vs Holley (who do you like best)

im running a 600 DP holley on my hot SL6 and i love it! get about 16-20mpg and takes off like a raped ape!

ive heard of some of my friends running demons and they arn't working so they break them down... they were full of metal shavings,sand... demons have a horrible quaity control but heard they are amazing once tuned.

i would just be certain if i bought a demon to pull it apart and clean the whole thing before it ever saw a car....