I've owned Naish, Slingshot, North and now Epic and Blade. The Epics look as well-built as any kite on the market, actually a little better IMHO. I did upgrade the plastic pulleys to metal ones and it seems to "eat" at the bridal less. You can also use rings if you don't like pulleys. Also, the section of line that the pulleys run are just a piece of amsteel line and are really easy to replace as is the depower rope(I keep a few spares I purchased at West Marine in each bag).
The only Blade kite I've owned is the Fat Lady. At first glance, the light weight of the kite and the skinny struts made me nervous cause I drop my kites in the surf, especially in light wind. Today was the first day I actually dropped it in heavier surf(head high) and it stayed inflated with 9 psi and no rips.
. At Billie: I had my 2010 Rebel repaired three times in the same area(floating strut) caused by waves much smaller than today. After the third repair they finally got it right tho, all warrantied.
Even after the issues with the struts, I still think North is built solid though, just bad strut design that year.