I will point out that neither service appears to directly tell you your box is oversized. That is only conveyed indirectly, by a big price bump over what you might think reasonable. I shipped a wheelset from Evanston IL to Oshkosh WI recently. I couldn't figure out why both were quoting relatively astronomical prices (about $50). It wasn't until I went to the post office to see what they would charge that the counter person told me my box was too big. I cut it down by a few inches and magically both services' quotes dropped by more than half (< $20).