These are street legal in Michigan if you stick to the lower K's like 5000 and 6000 temps. Michigan states that you must have white lights and no more than 4 forward facing ones at that. 8000K is iffy, 10K is definitely blue. I haven't had anyone pulled over for Xenon, one guy for bad aim, he rushed me on the install and didn't let me aim them, so he called up laughing 20min later. Just got a warning to fix it. I know him real well and told him it was just because you were black in Rochester and had to have some excuse when he realized you weren't a ninja and you drive clean.
Silverstar's suck, yes (as far as life). These HIDs have an advertised life of 30k hours, halogen is about 8k hours. I'd say realistically, if you get 15k, you're doing good. I've had mine in my Jeep which rides like a brick for 2 years now (and do alot of night driving), and some moisture got into the one headlight housing and even then it hasn't gone out yet.
I'll warranty these for as long as I sell them as well within reason. I've never had a warranty return on a bulb, so obviously if you go through 4 in a month I'm going to tell you you're doing it wrong or something.