I'm sold on turbo's. They can live a long life with smart maintenance, good fuel, and a great install. I'm lucky to be able to ride with a lot of turboed sleds, many with high miles. The highest mileage turbo I've ever seen was an '07 M8 with over 8k mountain miles. OVS turbo at 15 lbs. The owner put a new top end every 2k miles. I saw this sled back in 2011.
The highest mileage Pro I've seen was a '13 with 7200 and a '14 with 7500. Both BD race kits, 10 lbs boost and both on their 2nd top end.
I feel install is key, and then keeping everything clean and tight afterwards. New reeds with every top end (probably 600 miles on high boosted Cats).