What is causing you to need to upgrade to 8K's? Are you overloading the 7k's or just looking for insurance. Part of the reason I picked our unit was the fact of lots of load carrying room with the 7K axles and my shorter style trailer. I can carry about 4K worth of stuff that I am sure I need.
. I am not sure and did not look up your trailer weight numbers to see if their is an overload issue. I really liked the oil bath/disk brakes on some of the DRV Mobile Suites which were 8K axels. I would think they are superior to our grease style axles.
Tom Marty