Here are my thoughts on my '07 LBZ, now that I have 50K miles on it. I bought it new Approx. Dec. 1st 2007.
Basic Mods - FASS
straight pipe downpipe back, stock tune, Merchant
13 around town
9.5-10.5 towing average ~24K lbs.
20 empty on highway
Stock Tires - They lasted me about 45K miles, they still had "some" life in them, but it was getting squirelly in the rain.
Oil - I have been running Schaeffers 900 full synthetic since the second week. No problems with oil analysis. Change it every 10K
Fuel - No problems, change the filter every 15K miles
Tranny - Full synthetic Schaeffers oil, tranny filter every 10K
Rear and front diff - Changing this today, I will report any info.
Towing - Tows like a dream, no problems.
Interior - No doubt about it, the interior is smaller than a Ford, just can't get around that. Seats are holding up great.
Overall - I love the truck, don't regret changing to a Chevy at all.