I use UPS almost exclusively for kits unless they're oversized. About 2 years ago, after wrapping the kit box in brown paper and marking fragile, it didn't survive at the other end. Since then I have reinforced the inside of the original kit box and used that to ship at least 30 planes since with no damage whatsoever. My intuition tells me when it was wrapped, it was handled like last week's leftovers, but when the contents are known, the handlers/drivers take a little better care. My 2 cents worth from experience and I'll keep my fingers crossed.