It's good that there's a fair bit of competition out there. I would go with who ever is willing to fit it and offer warranty locally, saves the hassles later on if something does go wrong. Seems old mates on the money with it. No two boxes are the same. If it was me I wouldn't build it and go Cyro NO way, billet all the way even though Chris haven been proven to be ok. Best bet would be to ask what the box can handle and make sure it's warranted for that. Does seen like there's a good zf builder in each state so choice shouldn't be to hard