We just last week received a Stealth upper that I had ordered for my buddy back around May 1st. This thing is built like a tank and it is very well put together. I was very impressed with the product right out of the box and the early report is that it runs like a champ and is very accurate.
I don't have much experience with Spike's. Their upper does look very nice and close to what LaRue is putting out.
What I have come to love about LaRue is their customer service though. When you call, someone with an understanding of the products answers the phone, in English, and will give you answers, even if they have to put you on hold to get the right one. I like that. Their warranty is as good as it gets in the industry (if you aren't happy, we aren't happy) is tough to beat. Now, I haven't tested that warranty with something that was clearly stupid, but I have never had any problem with LaRue even on returns.
I would love to see an upper to upper shoot out though. Get on that, would you Slo?