First let me say that I do like this shoe, however, I think I liked the Landreth 5 better.  The 5 seemed a big more stable on longer runs; whereas the 6 is a bit more mushy/wobbly once your legs/feet get a bit fatigued.  I am hoping that the 6's lose a bit of that mushiness, once they get more miles on the sole.  The 6's have more cushion than the 5's.  All and all, I run pretty fast in these shoes.  The energy-response is good.  Another change in the 6 is the tongue is way too big.  It serves no purpose from what I can tell.  I'm not sure how they went from a short tongue with the 5 to a extra long and wide tongue in the 6....  None the less, it's a good shoe and I'm glad I have them.